You made a very wise choice whether you know it or not. You said your garage used to be 22x22 but is now 17x22 due to the new wall for storage. Having a room that is equal in length & width is THE WORST for acoustics. The cancellations would have been horrible!!! So by physically changing the dimensions you saved yourself some MAJOR headaches.
As far as the actual room, you have done an excellent job in both design & workmanship!! Kudos to you on the new theater!!! Very well done with the absorbtion panels, speaker placement & overall "Classic Cinema" feel. I really like the idea of dual 15" subs
Im running a 12" & 15" but im splitting the bass between them (90-50hz & 50-15hz)
Id give you a solid 8/10 for an overall rating. Im pretty conservative on my high ratings only because i know what the possabilities are out there. So an 8 is very very good in my book!! (for lack of a better description)
WELL DONE!!! ENJOY!!!!