Can't offer any input into other D200 grips, but I did just move up from a D100 with MB-D100 that I used for almost five years without incident. The battery retainers always felt solid and I had full confidence taking batteries out and putting them in. They just had that confidence-building mechanical feel that well designed parts have.
That said, I was instantly disappointed with the MB-D200 in this regard. The clips feel VERY fragile and I've also noticed that the door doesn't always close quite all the way unless I push it shut on both ends before turning the latch. My guess is that the MB-D100 used a pretty solid piece of plastic for the clips with a metal spring to return it back to position once the battery was in, and for the MB-D200 they decided to save money or space and simply deflect the plastic clip to create the "spring."
I think I may strongly exercise the clips on my MB-D200 20 or 30 times tonight so that if they're gonna break, they do now while I'm in warranty! This is not very encouraging. I may also see how much it would cost to invest in a three-year warranty extension.