Here's my take - I had both the iPad 2 and iPad 3 (after comparing them both side by side, I sold my iPad 2). I'm also a software engineer and have developed device drivers for S3, 3dfx, ATI, AMD, and Microsoft. The iPad 3 runs a little warmer than the 2. This is no big deal and is of no concern what so ever. It's within spec. Also, all modern ASICs have thermal protection designed into them. No one, not even consumer reports, has induced a thermal shut down or witnessed any software errors due to heat. It's a complete non-issue.
As for the wi-fi, my iPad 3 does get worse reception than my 2 did in the exact same spot. It still works. It's not a problem. It's just that this is a different device and probably has a different antenna configuration etc. I've got several laptops and they all get different reception. Both iPads get different reception based on how you hold them. If I'm laying in bed with the device in landscape mode with the home button on the left, I get one bar fewer than if I flip it 180 degrees with the home button on the right.
In my opinion, the only reason to get the 3 is if you LOVE the screen. I read a LOT on my iPad so that was my sole reason for upgrading. Side by side, there are many cases where the iPad 3 is actually .5 second or so slower than my iPad 2. For example, in the maps app, the 2 renders faster. That is, off course, because the images are lower res. When the 3 does complete, the results are noticeably sharper. It's the same case with many websites. There are games that are smoother on the iPad 2 because the iPad 3 is rendering so many more pixels.
As far as net "horse power", I don't think the iPad 3 is really any more powerful than the iPad 2. The A5x and extra RAM are needed to provide the same performance while rendering 4x the pixels for the new screen. For me, I'm perfectly fine with this. I didn't buy it thinking it was a more powerful tablet. I just wanted the sharpest screen I could get.
If I were you, I would go look at both tablets in the store side by side. If you don't notice the difference in the screens immediately, you'd probably be perfectly happy with the 2. If you need someone to point out the differences, then they probably aren't that important to you. You can get a killer deal on a used iPad 2. I just sold my 64GB wifi for $450.