I just read through this whole thread and thought I might help share a little bit of my personal experience. just to help ease this decision for you. :idontknow:
So I'm running factory rubicon D44s, factory lockers, regeared to 5.13s and 37s.
I wheel the jeep what I would call "CHALLENGING" but I keep the speeds down, hense not "hard wheeling", but I like a challenge, and usually take the harder lines up almost every obstacle around here...
Aside from bending a factory rear 44 axle flange, and twisting the splines on the other factory rear 44 shaft, I have had no issues with the axles. I believe both "failures" occurred while bumping obstacles, but its hard to say for sure. Though it is important to me anyways to not that neither of which stopped me in my tracks or needed immediate attention. Since then I have replaced the rear axle shafts with Revolution shafts,(lifetime warranty) I have yet to have another issue from the rear.
The rubi axles have their downfalls, but honestly; If you keep your speed down on the trail, you will be surprised how much of a beating they will take. Sure I WANT ProRocks, but only so I can travel a little faster on the trail and not worry so much about it...
anyway, hope my rambling here helps put your mind at ease with your decision. :idontknow: