I think the Wicked Edge is the most sophisticated of the clamped systems. And the KME is the least expensive clamp that will give you amazing and very precise edges, because of much tighter tolerances of the system. You can still get sharp knives with the lesser priced units, but they are just a bit too sloppy for my tastes.
For non-clamped, Edge Pro is the way to go....as a guided system. Or just take the time to learn to freehand. Unfortunately that is not an option for me with my lack of coordination.
Some like being clamped up, some don't. For me, I think it's the best way to get amazing results with the smallest learning curve. So my vote goes to KME as the best bang for the buck. The KME Gold Diamond stones do just fine on D2, M4, 204p, etc.
But, I also think everyone should have a SharpMaker handy with any of the primary sharpening systems. Once you have that perfect even bevel on a knife, there is no reason to have to go through a full sharpening down the entire profile to just touch up the very edge during use. And I think the SharpMaker medium and fine rods do just fine on the above mentioned tough steels when just touching up or adding a new micro bevel.
Just like a chef may only get their knives sharpened every so often (weekly, monthly, less?), but will most likely swipe their primary knife on a honing rod (steel, ceramic, or otherwise), one or more times throughout a days work. The SM is a great tool to have handy to simply touch up the blade back to that laser edge.
My personal philosophy is that once I have that perfect edge geometry in place on any particular knife, it will most likely not need a full sharpening again unless it's just really been beat hard, or the edge is chipped. A few swipes on the SharpMaker when I notice that the edge is less than perfect, will usually bring it right back to perfect.