Sparky76, I've never heard of anyone having serious vibrations due to the drive shaft. I'm thinking that someone ran over something or bottomed out somehow. Also, sub frame connectors are more than just a good idea when you start getting into the heavy mods. But for regular driving around and an occasional trip to the track, stock is fine. You won't hurt or twist anything.
I know quite a few people w/ 4th gens and it's pretty much the same across the board...they are very reliable. I'd say, the only recurring problem w/ my 4th gen is the brakes...actually it is specifically the rotors warping. It happened on all 3 of my 4th gens. Of course, there are a lot of guys complaining about loosing the rear end and breaking drive shafts. But, then again, those are usually modded up and are not completely built to handle the extra added power.
If you are serious about getting into a 4th Gen, there are a bunch out there that are really nice. It is not difficult at all to find an 01/02 w/ LOW miles and in a good price range. If you don't find what you want, wait a couple weeks and you will find what you're looking for. Good luck!