Keeping stock shafts, or getting alloy 30 spline shafts, is fine......but, if you're going to get gears and a locker, and will end up with 35's, and are likely to/willing to get alloy shafts, there's no reason to not get the 33 spline Superior shafts. IMHO
Once you have the 30 spline locker, you can't go get 33 spline shafts later. I can tell you from experience, it's nice to have the piece of mind of having big rear axle shafts. I've seen alloy 30 spline D44 shafts break with 35's, and I've seen alloy 31 spline 9" shafts break with 35's.
No question a 14 bolt is strong, but it's also big and heavy, and low and wide. It's just not a viable option for someone who plans to run 35's.
Why is it that you can't have a thread about rear axles or axle shafts without someone saying "just get a 9 in".
Yes, light weight, and strong, but the lowest pinion out there by far, and that is a definite negative. Plus, if I was getting a 9", and was doing gears and a locker, I'd go with 35 spline shafts at the same time..........just like going with 33 spline shafts if you're starting to build a rear D44.