cv shafts are stronger on a locked axle when you have the wheel cranked, (they dont loose strength in lateral motion)
U-joints you will sometimes bind the shaft at full lock if your on the gas, but when strait they are much stronger, Iv ran both, broke both and i run u-joint axles now and have gotten away from the cv's, only nice thing about cv's is when they break you can drive them off the trail and they wont wipe out your ball joints,
I dont have that problem and more, i run alloys and ctm's, id never turn back to those now either.. my 2c