I love my M1 to death, even though many would say such an OS mid would be uneccesarry. I tend to agree somewhat, since I don't use the M1 all that much but I do have a tone-pole ace with it, so I must be doing something right.
As others have said, the Gator is a slow, glideless brick with a massive fade, or hook, at the end. Which is actually a good thing for those crazy placement, hit and stick shots. The m1 is more versatile for me...its is quite a bit longer and has really good glide...almost Euro glide. I use my Roc3 or M3 for most mid-range shots, but as you can tell by my sig, I've got a lot of OS mid-ranges as well. I use almost all of them on the reg...I know, I'm weird.
I can tell you this: the M1 and the Gator feel vastly different in the hand. Like, no similarities at all. So if you don't like the Gators feel, then the M1 could be a viable choice just know that just because it's an OS mid, doesn't mean it is the same disc...like, at all. I now prefer a Breaker for my Gator-esque shots, and even though it's a putter I do find it to be a bit longer.