Race holsters aren't really that much faster on the draw and they are definately slow to reholster. Also the ease with which most draw means that the weight/inertia of the gun itself can cause it to bounce free with vigorous movement like running or jumping if they are not locked in perfectly, though this is not usually a problem in IPSC. I also think guys like em so they can show off their 5000.00+ race gun and 200.00+ holster.
Basic usually equals reliable, ie Blade-Tech. You'll see the same reliabilty difference between factory guns and race guns unless they're really expensive. As a bonus a blade tech is much cheaper. Most guys in IPSC are gear fanatics as well and that's also why you see so much whizzy stuff, but everyone including the gear fanatics will tell you you can't buy speed and accuracy.