Is it worth it?
I am on 31's and have wheeled my rig very hard, hard enough to twist the splines a little bit on chrome moly axle shafts, good shafts too, old superiors when they were made in the USA. I have destroyed several sets of U-Joints but have NEVER spit a cap. I say its worth it, even on 31's. If you run a lot of larger rocks on 31's your going to use the throttle hard, especially with stock gears ( I am on stock gears). Its impossible to say I would never have spit a cap if I hadnt gone to full circlips, but I can say that after 9 years on the same set of axles doing all sorts of stupid things and trails that are "35 minimum" on 31's I have never spit a cap. I would go full circlip.
John