Pretty much the whole reason I have Hangar installed is to make a neato asteroid base that has it's own defense ship, or can service visiting ships. I'm working on one right now in fact!
And in that vein, while I understand that having attachment nodes on both sides of the gateway doesn't make a whole lot of sense with the doors and all, it would really help out mission planning, at least for me. (currently I've got one hatch w/ a mine attached, and I'd like to send up another hatch and a gateway in one go). Would it be hard to make it decouple on that node, and add in a decoupler texture that shows up when you attach something there?
In any case, thanks for the awesome mod, I always manage to get my part count up there, so having hangars as an option is really nice.
P.S. are there conditions to meet before a hangar will accept a vehicle "in flight"? or is there a wiki or forum post I should read to answer that?