On the steel question, I am not sure which of those two performs "better" as treated by Benchmade. I have three knives in S30V and they all sharpen a little differently. The Ritter seems not to take as keen an edge as the Spyderco, nor hold it as long, but the edge is a LOT thinner, so this may be the result of Benchmade heat treating for a bit more toughness. A friend has an old Benchmade AFCK with an M2 blade and that cut like a razor and held it for a long time. I would very much like to have something made of M2, but as yet don't have much experience of it. The only thing is that the M2 version, being non-stainless, has a coating on the blade which may drag a little when slicing food.
Since I use the Ritter for food prep I am happier with the stainless version. The M2 is interesting due to edge holding and novelty, as far as I am concerned. I know that Bardster has both versions, maybe you could poke him for more feedback...there might even be some info over on British Blades, I don't know.
As to the Sebenza, well, I have the new style (as opposed to the "Classic") in BG-42 and while I love it as a piece of engineering, I have rather gone off it as a using knife. I carried it for the best part of two years and initially intended it to be a folding bushcraft/outdoors knife. I found fairly quickly that the convex secondary bevel, while sharp, was too obtuse to cut wood, and the narrow handle, which made carrying it so nice, bit my hand if I put real force behind making feather sticks. These are not things that the knife was designed to do.
As a tough utility knife it was pretty good. Two things happened that made me stop carrying it. First, the one I had had a detent that was too shallow and one day it opened in my pocket...no injury, but a clear sign that I needed to get it fixed. The Chris Reeve service was excellent, I wasn't charged anything, the knife was returned having not only had the detent deepened, but the handle re-blasted, the blade re-tumbled, and the edge honed back to original condition. I would have been over the moon, except that I had spent quite a lot of time turning the convex bevel into a flat, and reducing the angle so it would bit wood properly. Also, while without the Seb, I felt a bit un-dressed, so bought a Combat Elite RRF which sports a titanium handle and S30V blade, but is about $150 cheaper than a Sebbie. I found that with but one exception the RRF was a better utility knife than the Chris Reeve, it even cuts wood better. So when the Seb came back all prettied up, it got packed away into its box.
Another good reason for using the Ritter in the field instead of the Sebenza is the cost, one cost about $105, the other at least about $350
There aren't a lot of folders out there that are really designed for outdoor use. Some are meant as hunting knives, some are more general use, but the Ritter has been put together with a blade designed for outdoor tasks, and a handle with better than average ergonomics. The only other folder with similar pedigree that I can think of is the SERE 2000 (can't resist posting this link
http://www.kingsley-hughes.com/outdoors/kit/kn.asp) The Ritter though is a LOT lighter and less bulky, so is easier to carry.