One thing that I'm also curious about is how long have the folks who've had "no problems at all" owned their Jeeps and how often (and for that matter how difficult of terrain) do they wheel? I've seen a lot of comments on this thread that say "I've wheeled it like this for three years and it's fine". To me, three years isn't very long. After another seven, let me know how it's doing.
I'm an occasional wheeler (8-12 weekend wheeling trips per year) and run trails that are moderate to nasty as well as a fair amount of street use and foul weather driving. I'm very easy on the skinny pedal (I don't like to break things) and I'm currently on 33 12.50 15s.
Over the 15 years that I've owned my Jeep I've bent a housing (slid off a honk'in big rock going up a creek bank), broke a driver side shaft (while climbing a hill a large rock rolled loose under the tire and when it caught purchase in the dirt under it, it snapped), and I currently have a bent passenger side shaft. I'm not sure when this last one happend, as I didn't realize it until they raised the speed limit on a highway that I frequently drive (vibrations only occur above 65mph). All of these (except maybe for the last one) happened on 31 11.50 15s. I've wheeled it a few times (some very, very rough wheeling) since going to the 33s and haven't had any issues.
A lot of people might say that these were flukes and that I've had good luck given the amount of time, but I have to disagree. I'm not saying that Jeep should have put a different axle under it, I'm just saying that it's not "worry free" on tires 31" and taller. I've owned and wheeled several different ORVs. I never worried about the axles in any of them. I worry about it in my YJ.
That's why it'll be getting an 8.8 in the near future. Since I've got parts set back for a stretch, I figured that I'd wait until then to put in an 8.8 (no sense messing with driveshafts twice). That's the only reason that I'm going to bother fixing the d35 for a 3rd time. I'm considering it a stopgap until I get around to the 8.8.
Since the OP was trying to make a decision, he needs to ask himself this:
Do you wheel anything more difficult than "moderate" trails?
Are you running (or do you intend to run) tires larger than 33s?
Do you run (or do you intend to run) a locker in the rear axle?
Do you wheel agressively (hard on the skinny pedal)?
Are you willing to risk having to do a trail repair of this type?
If you answered yes to more than one of the questions, it's time for an axle upgrade or swap.
If you answered yes to at least one of the questions, it's time to seriously think about and axle upgrade or swap.
As far as upgrading to a super 35 or swapping in an 8.8, that's something you really need to research and decide for yourself. The way I look at it, for the price point, I'd rather go with an 8.8. You still have a lot of room for upgrades if you break them. With a super 35, you're sinking a lot of cash into the axle and you still can't go above 35s. If you start breaking stuff in a super 35, there's no where to go but axle swap (you can't really "upgrade" your R&P...). If you can do the work yourself, it should be cheaper to do the 8.8 (unless you buy an ARB to go in it at the same time).
If (for whatever reason) I wasn't in a situation where I could do the work myself and I knew that I'd never want more than 35" tires, I'd probably just go with the super 35 with a truss (and I'd still worry about the R&P). For me, the 8.8 is a no brainer. I turned down a deal on a non C super 35 with a truss, 4.88 gears, and disk brake conversion for $500. I've wondered if I made the wrong decision, but it'd been wheeled pretty hard and I'm seriously considering eventually running 37s (and I don't want to worry about the R&P).
“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.” ― Robert M. Pirsig, Zen And The Art Of Motorcycle Maintenance: An Inquiry Into Values