I prefer the .38 Super rimmed case as it's design assists in the feeding cycle (from the magazine, up the ramp and into the chamber). As the slide cycles rearward, it contacts the round in the magazine. On the Super, that would be the rim, thereby tipping the bullet nose slightly upward and allowing it to contact the feed ramp at the correct angle.
I have a couple of friends that are shooting 9x23 and 9 Super Comp (also rimless) and they are also the ones who tend to have jams at the worst possible moments during a match. One of them is actually a full time gunsmith.
FWIW, most of the Open Master class shooters around this area are shooting Super and have been for years. The nickeled cases tend to last longer but that may be because they are easier to find on the range floor!
YMMV,
DblTap
[This message has been edited by DblTap (edited October 06, 1999).]