Our limited experience with the DA keeper training is that it was excellent, much better than what my boy received from his club. I'm in the minority regarding keeper development in that I like to see my boy play on a team that sucks. He's had opportunities to play with teams that would have him stand 28 yards from goal watching and watching. We have been fortunate enough to have chosen teams with weak defenders that have allowed shot differentials of 3-1 putting him in the action more than the typical USSDA keeper.
Here we sit in June and my U16/2003 who two years ago was a U14 playing on a U14 flight 3 team, then the following year as a U15 moved to a U16 (2002) Flight 2 (up 1 year) and now this fall will be on a U18 (2001) (2 years up) Flight 1 team.
I believe that the best development occurs during GK training and practices. With the average GK getting less than 10 minutes of actual game involvement (i.e. shots, corners, etc.), I don't see the games as contributing towards the major part of development, unless the team is weak, then the keepers is going to be in the action a lot.
So in my opinion the USSDA should result is excellent development, not because of the games, but because the keeper training should be excellent and the keeper will have significant development during the 4 practices a week. The games won't and don't add much to the overall development of keepers, but merely allow the keeper to hone and demonstrate skills learned during training.