Interesting. I have an iPad 3 that cannot connect to wifi (or even find the network) in spots where my iPad 1 can. I had chalked it up to just being not as good at certain things (but certainly much better in others). Certainly, I can say that if the 3 is supposed to perform at least as well over wifi as the 1, there is some sort of defect in my unit. I guess I'll bring it in -- although I don't really like the idea of paying for new and winding up with a refurb.
By the way, the heat issue has not bothered me at all, and I am generally very happy with the 3. When the unit first came into our house, my family was slow to take to the new one, and the wife and kids were sort of indifferent between using the 1 and 3, but not surprisingly, over two weeks the benefits of the 3 have become very obvious, and the 3 is the greatly preferred unit by everybody. Aside from the wifi, the only point of less than complete satisfaction is over the battery life -- the 1 lasts so long that I don't need to worry about it, while the battery life of the 3 requires you to pay more attention to the level of charge, etc.