Wow, this is amazing, the only thing that's bothers me is it's size. It's small and crowded, next urban spar location should be a garage, or a plane hangar.
So I did try it out with both you and Tyzi. I can't say I found anything wrong with it.
The walls around the place gives it a good feel imo but it's also hard to use anything more then just that. Climbing up the walls will rarely happen so maybe try making both elevated and lowered areas in some future mod? It's a good mod though, great job.