I tried two iPad 4's and returned to my 3.
The speed was nice and gaming was considerably smoother but I don't game much at all
Image retention issues, yellow backlight bleed, poorer construction, "dynamic contrast issues" WilliamG draws attention to in the iPad sub forum (inherent on seemingly all 4's and no 3's) was enough for me to return to 3
I lost like 50 dollars in the process but still worth it since screen is key and I went through too many 3's before getting this one (I swear the good run DY serials have Sharp displays since this doesn't have multiple tint like launch Samsung screens and no IR or yellow bleed common on LG's)
But I like where your thinking is at.
Hopefully with mini2/ipad5/iphone 5S (maybe 6 also) the devs can take a crack at iOS 7 quickly especially with exploits being reserved but I WOULDNT WAIT or dare try to predict when it'll happen; you'll go nuts and if history is any indication it might be a while.
I might ride my 3 out regardless. For my uses its been bliss. I'm actually impressed how quick it is, all things considered