The buttons crapped out on my hardware M-1 years ago. I never looked back in buying the software version of it. If you remember the cost of the extra sound set cards back then, you know what a deal it is to have all of those included on the M-1.
I always thought many of the sounds in that keyboard were a little washy in reverb but that can be changed in the FX settings, it was all in 16bit but I can't really hear a difference in a mix most of the time. As a multi it's tough to beat on a computer compared to something like Kontakt that might strain some computers with heavy mutis. It works light and sounds good.