Which 10 spline HD shafts? fancy some myself.
The problem with 10 spline is that at the root of the spline there is a stress raiser, the shoulder of the spline. Having 24 obviouosly spreads any load out further but then the splines are not as deep either, which is good plus the profile is differnet, again avoiding the sharp corners of the 10 square splines.
Heat treatment and better alloys will make a big difference, but out of the box 24 splines are better.
Here's the downside, once worn 24 splines are a bigger liability than 10 splines because the loaded edge is at 45 degrees to the surface of the shaft, not 90 like a 10 spline, so when they wear they jump.
If you have lockers I'd suggest you use them wisely and leave them where they are, I havn't bust a halfshaft yet.
