My last match had 3 lvl 30's and 2 lvl 1's on enemy side, I played support and had a vayne with me vs a jax/lulu, I ended something like 3/0/16 and vayne went 16/0/3. My lane partner was lvl 21, im 20, the rest of our team 17.
They /FF at 23, only lane that we lost was mid cause our Anivia decided to go top with our panth and let our jungle shiv take mid lane vs ahri. Early game was scary and we got poked out of lane twice, then at 6 I landed a 3 people crescendo under our turret, vayne picks a double and I pick up 1, one minute later vayne picks up 2 in bot and 1 in mid, the snowball began.
Only real difference of a lvl 30 vs a low lvl is early game, imho.