Kydex is certainly prefer to leather. Lots of good choices. Uncle Mike's and fobus are cheap but work fine for beginners. Blade tech, comp tac, Center of Mass kydex, and others are fairly similar in price and all work well. These dealers also tend to have some type of competition pack which includes magazine pouches.
The biggest advantage of kydex over leather for competition is the smooth and consistent draw. Leather binds. Having it stay open after the draw is a benefit however using your leather holster should not be a safety issue.
You are never required to reholster on the clock. Take all the time and care you need to reholster your gun safely.