Before I start giving my opinion about Quinn and Valor and the kit given to this champion I am first going to start off by explaining how long I have been playing this game and that I do in fact know what I am talking about. I have been playing League of Legends since the last week of the beta. Carry roles have been my favorite for a long time, however I have and can play any role in league of legends at a competent level with at the very least an advanced knowledge of my role relative to my team and the enemy team.
Now that being said lets dive into Quinn and Valor.
First and foremost is the auto attack range. 525 is not enough without at the very least 1 true escape (an escape move that does not require anything other than the press of the key like graves or ezreal e). Why is this? Doesn't she have a blind and a slow? Isn't that enough to let her escape or outplay her opponent? The short answer is no and the long answer is sometimes. If we were to take a look at graves we can easily see that this champion is very well suited for his role and in fact is a little too well suited. His 525 range is the only reason he is even balanced because he has so much utility in smoke screen and his dash for escape and dps. Now lets look back to Quinn and Valor who if released as is will be the only other "adc" in the game to have 525 range. What can Quinn use to escape or outplay a situation? Her e sets her back to AA range, 525 which is WELL within MANY skill shots and ones that cannot be dodged like Ryze's Rune prison which currently has 650 range. Also as a side note I would like to remind you that even Caitlyn has a better escape because even though her net can only move her 400 units in any direction it is not relative to an enemy or neutral monster and therefore does not have to place herself in danger to kite despite the fact that she has one of the longest AA ranges in the game. The key issue with Quinn's kitting potential is that it requires that she "go in to get out" if using this ability which in the current meta of under powered adc and huge health tank bruisers is a recipe for death and loss of a game unless Quinn and her team are far ahead in kills and/or cs. Outside of this meta I have only one question to anyone who plays league and that is if you are playing an adc that has low range like 525 or even 550 like vayne how effective are you at your role if you cannot kite well in a teamfight? The answer is you are useless. You will die every teamfight you do significant damage in (assuming that the teams are even and the enemy team has half a brain). Especially with how broken randuins active is for the cost... but thats outside of the issue here.
Ok so her E is probably best used as an offensive spell unless it can place her over a wall to safety whats next? How about her ult? Well yes her ult does seem quite good for getting away except there are two key problems with her ult. Number one is the cooldown time. Its so long that if Quinn has used her ult which is her only real kitting move in her kit it probably will not be back up in time for a fight (possibly even 2) so it is not reliable and if anything is a liability. Which brings me to my next issue with her ult which is that when activated she becomes a melee champion. As adc is my favorite role in the game I can honestly say from any hardcore adc players perspective why would I ever want to turn into a melee considering the items I will be building to make me an effective adc? I have little to no health and the ult itself does not provide me with anything other than movement speed and attack speed so what good is it really other than to move around the map and take objectives, but in turn giving up my ONLY real escape move that has a long cooldown? Someone told me that it gives you chasing potential, but seeing as how this ability doesn't even reset the cooldowns on her other three abilities all you can do when you get there is AA and use the second cast of her ult in the hopes of bursting down the opponent (provided that you arent too low from a fight yourself and get outplayed or nuked immediatly).
So at this point I ask myself when would I ever choose this character as my adc over any of the others? Her only real useful skill is her q as it gives her a blind. That blind is probably one of the best possible tools for dueling in bottom lane. Not only is it a blind its also a nuke so by hitting Quinn's Q a player effectively blinds an area of enemies and does significant damage to them (provided the enemy is an adc or support as is common in bottom lane). This is invaluable and probably far too good and its why you feel the need to expose her to a 525 range with little to no way of getting out of a fight. The problem is that during a team fight even if Quinn is ahead by 15 kills she has no real way of staying away from bruisers and ap carries who can kill her before she can use that damage. Blind is not that useful outside of a duel especially when it only lasts 1.5 seconds. Thats plenty of time for an Olaf or a Xin to tank any damage Quinn can spit out if she isn't chain cc'd by the enemy team.
So how do we remedy this? What can be done to give Quinn and Valor a fighting chance to be a usefull adc? Well here is what I have come up with. First increase her range even if only to 550! Second take the blind off of her q and put it on her e so that it can ONLY be applied to 1 champion. Then make her e a dash move rather than a on click ability this way it can be used as an escape as well as a dueling tool while putting some risk and reward into the ability (also make it so that if the dash lands on a champion or minion(s) it sets her back to AA range just like before, but if it does not land Quinn is stuck where she is). Third keep her Q as is, but replace the blind with an on hit slow. This gives her some kitting potential and also dueling potential, but the ability has to land in order for her to get the benefits so she has thus become a skill based champ.
Personally I love Quinn's W and passive and think that these are great as they are, however her ult does need to be changed in some way. The easiest fix would be to lower the cooldown a little and possibly give her some kind of resistance or health bonus while in ult form otherwise going into melee form is a liability in a teamfight. I also have been toying with the thought of reseting her ability cooldowns when she activates ult form, but I don't know if that would make her op or not considering the possibility for double dash and super high movement speed. A health bonus or resistance bonus is necessary though.
All in all I love Quinn and Valor as a champ, but as it stands right now she has no chance of being an actual carry. With adc items as nerfed as they are I wouldnt be too surprised to see all bruiser team comps soon enough because adc's are quickly becoming useless. I don't know if this is caused by a fear of them being too op or not, but Riot needs to keep in mind that they are carries for a reason. They are high risk high reward champions essential to a team for their damage output. If they can't do damage for whatever reason then they are useless and will be replaced. Quinn and Valor as of right now will be used as a top or mid lane champ to split push all game like Nid. So in a sense she will carry the game, but not as intended. lol
Anyway thx for reading and if you made it this far well I'm surprised. I doubt riot will read this, but if you do please try to take what I have written into consideration.
QFT Though I disagree with some of your proposed fixes/changes. However, your assessment of her standing is spot on.