The main featureas and benfits follow:
Superzap's:
Goes to 2.5.2 or 3.1, but will not go from 2.0
Includes xplusz
With 2.5.2, no special hack or P4 required
With 2.5.2, no TiVo PVR tier needed on card
Doesn't mess with season passes or recordings
KRavEN's:
Minimal 3.1 install with only the absolutly essential hacks
Will upgrade 2.0 image as well as 2.5 and 2.5.2
Has seperate modules for each hack so that you can choose which ones you want
the 3.1 xplusz works very well with this image, doesn't conflict with hack modules, and if you uninstall, all previous hack modules will be active again
Doesn't mess with season passes or recordings
So you essentially need to decide what you want.
If you're a newbie that just wants it simple and everything done for you, go with superzaps upgrade to 2.5.2.
If you're more into the DTV hacking so you can figure out how to get past the p4 and tier requirements and want the benefits of 3.1 with it's additional speed, features, and code maturity, then go with my update.
Information wants to be free....