I owned, and loved, the M8. After succumbing to the allure of the FF M9, I believe the performance of the M9 does more than justifies the additional shekels. You get the advantage of shooting at actual stated focal length of lenses, image quality that is at least as pleasing as the M8, no need for use of IR filters when shooting color, a camera for which replacements for all components are still available, and (strictly from a monetary value standpoint) a camera that will likely hold its current value for a number of years, going forward.
I also own and MM1; and, if I were secure in my belief that B&W is, in all cases, the best way to shoot, I would consider that camera as the leader in value...the high ISO rendering is very liberating. However, since obtaining the M9, I find that its color rendering, with the 35 Summilux V2, has me gaining a stronger fascination with color images. The M9 is now my choice about 75% of the time.