You've mentioned everything except for the possibilty of going out and getting a job right now. If you move forward with an MSM right now and later pick up an MBA, you may end up wasting a year, real cash and opportunity cost. So, you may want to think about that a bit more.
Certainly the better the school you attend, the more access to opportunities you will have. I attended a State school for undergrad and I was blown away by the opportunities that my classmates in b-school who attended "brand name" undergrads had that I missed out on.
Just something to think about.