Dav: correct, D2 is also an excellent steel. An AFCK with an Axis lock and either M2 or D2 steel is going to be a *superb* knife. Hell, it'd be pretty good in ATS34; my only concern there would be that BM's heat-treat on ATS34 isn't optimal (in my opinion).
Here's why I like the Axis and M2/D2 combo:
The grip ergonomics, combined with a truly reliable lock and good blade.
The grip allows you to use the "slack forefinger/thumb" grips (Asian influenced) where the strength comes out of the back three fingers. It "bulges at the pommel" nicely, a feature we're seeing more of as people study Asian knife combatives, but comes to a WIDE flare right at the pivot to prevent "slip-up accidents" (hand slides down the blade on a hard-target stab, cutting the inside finger tendons).
The lock is first rate, the blade shape is plenty good enough (I'd prefer fatter, like an enlarged Ryan 7, but it's no biggie). And the clip is flippable for off-hand setups. If I had a CCW permit, I'd set up for gun at the right, knife as the primary off-hand weapon...there's a lot of utility in a knife that's southpaw compatible even for righties.
The Carnivore comes up a bit short on the blade length and lock reliability. A Rolling Lock works GREAT when it works right, but...they are a bit finicky and failures are really what drove REKAT under. I believe the Axis is a better design, the best lockwork available.
I just wish Benchmade had the guts to build megafolders. An AFCK "supersized" to a 6" blade would be just killer but...they're just not creative enough.
The other option: take the existing AFCK, and turn it into a Muscrat. A double-ended folder, two blades that open in opposite directions, with a 5" grip in the middle.
THAT would rock.