The answer: If you are a good player, yes.

Simple, should be common sense if you've played LoL for any length of time, but so many people want to whine about how starting with a TotG on some champs will give you another 80 mana, or how Yi won't kill as fast without lifesteal (wait wut?).

Silly whine is silly. Adapt, or pick someone else. People wanted a new game mode, why would we want this new game mode to play exactly like the one we already have?

I think lots of champs will even be more viable with new play styles. There are lots of champs that are forced into getting certain items because they are support or their ability to lane/farm effectively is lacking. Now we are going to have a game mode where there is no "Laning Phase". We are gonna have champs getting items they never had access to before. Not because it would be a bad build, but more because it wasn't viable for that champ to achieve in classic Summoner's rift.(lack of farming/supporting the carry)

i want new maps, not a new game

Summoner's Rift is the Perfect map for that style of game. You're not gonna get any better or worse without having to totally change balance and gameplay anyways.

That's why with Dominion they've already preemptively removed and added items plus created a global "Buff/Debuff" that applies in Dominion.

The most you can hope for is a map so similar to Summoner's Rift that it wouldn't really be worth the time. I think the 3v3 style map is the only viable option and still retain some aspects of the gameplay.