Read this:

http://www.gearinstalls.com/410suck.htm

That article really opened up my eyes and changed my thought process on the issue. Especially T-case mods verses diff mods and whole myth of 4.10s being stronger.

I think running a smaller tire is always going to put to less stress on the drivetrain in certain circumstances, but after reading ZUK's article, it seems to me that the quality of the gear install is far more important that what ratio you run, whether it's 4.88 or 5.29.

I know from my point of view, running a 22RE truck with a lot of wieght, the lower the ratio the better. I run 5.29s and 35s, but sometimes I miss the days when I had 33s with my 5.29s.