UPDATE on post 12. (TL;DR: great experience at 1200mile service. No issues to report; friendly staff, free coffee)
Anyone have service experience here?
My car came from NY, but I dropped off my 335is lease with Northwest (had to pick my M3 up down the street from an Audi dealer under the same ownership as the BMW dealer in NY). When I was dropping off the lease, the Northwest BMW dealership staff was really nice and welcoming even though they knew I didn't order my BMW through them. The guy who took my 335is also has an M4 so we talked cars a bit.
I also went to look for a car cover (should have realized there was nothing out for the M3 yet before going) and ordered some touch up paint. They were kind enough to let me know that the paint has an expiration date so I shouldn't buy it if I wasn't doing repair work immediately. Never had a dealership try and persuade me to NOT buy something
So... from those experiences, I am using them (over Towson, which is the only other dealership I've had experience with (and it was NOT good... not horrible, but sub par in the least)). I will be doing my 1200 mile service and will report back!
One last question... I have the BMW exhaust valve module in my OBDII port. I was planning on removing it before the service. Since it's not a tune, should I not even bother? Or should I play it safe and take it out? haha