I'm not a fan of the SERPA holsters.
Certainly, some users need the retention device offered by the SERPA, but I tend to think most don't.
I believe half the cost of a SERPA is tied up in the retention device, either in R&D or production costs. If you don't need that device, then you've paid $60 for what is essentially a $30 holster.
If you are looking for a range holster you don't need a retention device and I don't think most concealed carry users need a retention device either. The SERPA sticks out from the body quite a bit and doesn't conceal very well anyway.
Open carry users probably could use the SERPA's features to ensure the security of their pistols. If that is what you are looking for it would probably be a good option.
If you're looking for a range holster, in addition to the ones already listed you may want to try
Comp-Tac
http://www.comp-tac.com/
Blade-Tech
http://www.blade-tech.com/home.php