Yeah, scene management would be very very nice. However, perhaps it's best to ask JCL what and when he thinks he'll have something integrated in 3dgs. I'd hate to see you develop a great scene manager when 3dgs ends up releasing one of it's own. Though I must say, the idea sounds really intresting, and I have no doubts on whether or not you can pull it off.

btw - would you know of where to start to get 2 sets of uv coordinates in the .mdl format? Support for baked lightmapping would be really nice, I'm sure a large degree of users would pay good to have that ability. But mabye not worth pursuing if it takes a large amount of work.