yeah, depends on how much experience you've got and what kind of wheeling you are most interested in!!

Not really, I've got a good amount of experience, and I wheel mostly rocks (my 3.0 is allergic to mud) and I've still got the IFS.  I'm going to run it until its bent and tweaked to the point that it isn't safe to run, then go to the IFS.  I've broken a few halfshafts, but I've seen just as many birfs pop on the same obstacles, and personally, I'd rather replace a halfshaft on the trail than a birf.  Its all about being smart and knowing the rig.  The "less capable" a rig you start with, the more you learn.    Granted, a SA with longs, elocker, 5.29s etc. will give you more flex and articulation for rockcrawling.  Eventually I'll have one.

Personally, I'd put the $$ toward dual cases, if you're low and slow, you'll go many places the big boys can, and it doesn't really matter whether its IFS or SA.