Troy,
I've handled 3 of the 4 knives you mention, but haven't used any of them. So I can't give anything except a visual-inspection type impression, but I'll give it a shot anyway ... Please, keep in mind that often my mind changes radically after I actually test a knife, these visual-impression inspections are of limited use. In fact, don't look at this as something factual, look at it as a strawman to start discussion on these knives.
MOD Dieter: What I liked: This knife seems to meet the designer's stated goals. What I didn't like: but those goals are so far from what I'm looking for in a hard-use knife that I have a hard time judging it fairly. Carryability is a big concern of mine, and blade-to-handle ratio is a part of that. Bottom line: This knife is too big for the blade size for me to be interested in it -- if I personally found a lot of utility from the little hook in the end, I might re-think that.
Microtech SOCOM Elite: What I liked: Another fit-and-finish masterpiece by Microtech, and I love the overall design. What I didn't like: What I don't love are Microtech's locks, and I haven't seen anything to convince me that the Elite is any better. The Bottom Line: The Microbar is the only thing keeping me from picking up an Elite. That's just
my opinion of Microtech's locks -- there are plenty of others who disagree.
Outdoor Edge Impulse: Say, looks just like my Krait

What I liked: I'm impressed on what a nice job Outdoor Edge did. Overall, I find the design very beautiful, and a clever way to get a good-size opening hole. Darrel found a way to make a sort-of-tanto-ish blade reasonably useful, and I think he met what I think are his design goals (hard-use utility with
style ) just fine. What I didn't like: I tend to like a little bit more secure handle on my hard working knives, and prefer a thinner tip to a reinforced one. Bottom line: Great knife, but it's a liner lock, and I don't buy liner locks.
Spyderco Ayoob: This knife is different enough that a first-impression is probably not all that useful. What I liked: Typical good Spyderco construction, comfy and secure handle. What I didn't like: I'm just not a fan of the radical blade-to-handle angle. Maybe if I used one for a month, I'd change my mind. I've read several reports of people thinking they wouldn't like the Ayoob, then getting used to it and actually liking it down the line. Bottom Line: There is at least a niche of defensive-minded folks who are a fan of these exaggerated blade-to-handle angles (Szabo leaps to mind) -- but at the moment I'm not interested in it. For someone who is, the Ayoob looks very interesting.