Hello ellwood, I have owned quite a variety of both .38 super and 10MM pistols and revolvers, since the early '70s in the case of the Super. I have shot, and reloaded a fair amount, for both cartridges. You mentioned the Commander. My first Super was a Combat Commander ( steel frame) back about 1970 or so. My first Commander, and later '70 Series Govt., both had the earlier barrels that Tried to headspace on the semi-rim of the cartridge. Terrible!!! Inaccurate, flattened and pierced primers,etc. My later Colts, and one Kimber, had the barrels that headspaced properly on the case mouth like the 9MM,.45,etc. Problems solved. The best of the lot for me has been the Kimber Target II in .38 Super. Accurate, totally reliable, well fitted and finished, well supported ramp type barrel. etc. I much preferred the Kimber over my, considerably more expensive, Colt Custom Shop .38 Super Special Combat Government. Within my humble experience, the main advantage of the Super over the 9MM is with the 147 grain and heavier bullets. The Super may appear to be very superior to the 9, but most ballistics charts and reload data give Super velocities in 5" barrels, whlie reporting 9MM ballistics from 4" barrels. I have chronographed both from 5" barrels which show them to be much closer with bullets lighter than147 grains.
I have owned 10MM pistols and revolvers since about the time the 10 was introduced. I've had Bren Ten, Colt Delta, Kimber Eclipse, S&W pistols and revolvers, Glock and a Ruger Blackhawk in 10mm. I'm a 1911 guy and, obviously, a 10MM fan, but I have not found the 1911 to be the best platform for the 10MM. The Glock and S&W autos, with their heavier slides, handle the real 10MM ( 200 at 1200fps and similar) better than the 1911 IMHO. The Super, even in the heaviest loads, recoils much less than the 10 with the "real" 10MM ammo. Seems like some of the 10 now days is loaded down to approximate the .40 S&W. Obviously, with this ammo, the 10 has no advantage over the .40 S&W.
Anyway, both useful cartridges and fun to shoot and reload for. I recommend both.