BTW, excellent yard lead. You really will be able to have trains running while simultaneously doing classification work in the yard. John Armstrong would approve of your trackplan.
On edit: Traffic on the yard lead will still foul the inner mainline. I'm not sure how that would best be addressed.
I see a potential problem with the staging/interchange track. Because it is almost out of reach you won't be able to easily change consists. For me interchange is of crucial importance because it represents the whole outside World and thus the other half of operation. That is, I use my interchange track (which is actually a return loop in an adjacent room) as a fiddle yard where I build incoming consists using the old O-5-O switcher (hands).
Ya, on my list of #aroundtoits is to do a more workmanlike job of the return loop but in the meanwhile it does function as needed. The paintbrush, as well as being a dusting tool, indicates the next set of cars to be worked into a train. I don't use switch-lists or waybills but simply cycle through a set of possible consists. Someday when I'm really bored maybe I'll see if my math-foo is up to the task of determining the total number of consist variations and their frequency of occurrence. 
Lew
