Keeping in mind that every form of training is to some extent a game, in that your life is not really at stake and you are not going to kill somebody, I think Miggy and Cthulhu already nailed it---you certainly can get training value out of it. Depending on how inherently competitive you are, it may be hard when that beep goes off to think about training and technique rather than time. That's up to you, of course.
As for me, well, I will happily use my MTAC and a normal cover garment for local club matches. When I go to the sanctioned PA State match tomorrow, I will be using my Blackhawk and a shoot-me vest (and I would be firing powder-puff loads that barely make power factor if I loaded my own, too!).
