I believe there is another difference with the MM2. I went from a 7 1/2' MM to an 8' MM2, so it may be due to size, but the dealer did claim it was new to all. There is a much taller pin and a-frame at the pivot point between a-frame and plow making the whole assembly sturdier.
Using both, I still don't like the extra time for the lift, after the spring collapses the cylinder fully. It is time AND battery power. I am not convinced there is not issue with my setup though, since others have reported shorter lift times. But this should not be the reason not to buy it, just unhook the spring. Best of both worlds!
Without a doubt, the MM2 is easier to mount and unmount. I used to forget (anyone else do this?) to push up on the headgear while inserting or removing pins. The MM2 gives you nicer spot to push on and with your other hand, you pull the lever,and both pins come out. With the MM1 it always seemed like my arms were in the wrong spots, and I was always a second away from using the light to push on and breaking it off.