No offense, and I'm a Rubicon driver with large tires, I would have never put that money into a D44. It's almost like putting a super 35 kit in a Dana 35.
With that said, the weak links on the Rubicon D44's are the ball joints/hub bearings and rear locker. The ball joints will wear out fast. With 35's, I was replacing them about every 6 months and the unit bearing about once a year. The rear locker I broke on 2 occasions.
The only time I had 37's was with stock shafts, and that did not work. After upgrading to 4340's front and rear, I went back to 35's and had no problems. Since I wanted to have larger tires, I ended up swapping out the D44's for D60's and sold them to a guy with a 02 TJ. I never broke the 30/27 spline axles. I was not easy on it, and neither was Goat on his with the same spline axles (actually he had 33 in the rear I believe?).
I also don't understand why you have 35 spline axles in the front and 30 in the rear?
...Oh, and yes, the Rubicon has D44's under it. They are not D35/D30 axles with a D44 center.
In fact, they have larger ring gear bolts than a standard D44 does. The rear axle is D44 from wheel to wheel. The front is all D44 between the knuckles; but knuckle out is the same stuff Jeep uses on D30's. Not the true D30 that the CJ has, their bastardized version that they decided to start using in the YJ's and forward.