differences between old an new buck marks?

I understand that the newer version Buck Marks have "ears" on the back of the slide for better grip but what else changed with the newer models? If I can get a good deal ($200) on a new older model Micro should I get it or hold out for a newer one?

The slide extensions are not the only differences between the two generations. The entire slide assembly (which include the internals) is new. AFAIK, that is the only change. I'm pretty sure the new slide assembly will work on the old frame but haven't tried it yet. I'm planning on upgrading the old slide of my Unlimited to the new slide assembly. The extension is, IMO, a great help if you buy one of the models with the Weaver-type rail on top. The rail is wide and getting your fingers on the recessed serrations is difficult with the old slide.