I always seem to buy carbon steel benchmades...I've had the D2 cabela's minigrip, 41mc, 960 and 32 morpho. Every Benchmade I've bought with the intent of me keeping it for myself has been in D2, actually.
Too bad the M2 disappeared before I could play with it.
In any case, all the Benchmade have performed pretty well. The most recent, the 960 and morpho, came far sharper than the 41MC and cabela's minigrip I bought a couple years ago. Those two are brand new, but the old ones held their edge quite well and I never had rust problems (unlike some of my stainless steels recently).