Don't worry about the strength of the 10 bolt. In original trim, it is almost equal to an original trim 12 bolt in strength. If you need more, upgrade your 10 bolt with stronger parts rather than spend tons more for a 12 bolt.
The weakest spot on a 10 bolt is the axle tubes where they are welded into the center section.
Dave Henninger and Kurt Urban ran their blue 70 Camaro into the 8's with their 8.5" 10 bolt and never had issues. As far as welding the axle tubes,the 12 bolt has the exact same tubes,and they need to be welded too,so there is no difference there. Theyuse all the same size bearings,and the 10 bolt uses 10 7/16" bolts to hold the ring gear on which is techincally more bolt then the 12 bolt's 12 3/8" bolts. Aside from the 28 spline axles,there is no real difference.