I have a 201 Activator in D2 that I have owned for a couple of years, but never used. Haven't handled an RC-3, but I have been thinking about buying an RC-3 or RC-4. Here is my take the 201.
I believe the 201 blade is thicker (.140 vs .125) and not quite full flat ground. I believe that it's higher ground than most BM knives, but I am not sure of the angle. It's not particularly sharp though, typical BM. The blade has a slight recurve that looks good. Don't know how difficult it would be to sharpen. I think the blade is thicker than it needs to be for a blade this short.
The scales are well finished wood, but small and very smooth, not much to grip. The sheath is reasonably made leather, which is traditional, but not too practical IMO. Over all, the knife looks and feels stout, but elegant.
I am not sure the 201 is a keeper, but I can't bring myself to sell it either; it's too elegant, and I like the idea D2. I've thought about having a Kydex sheath made for it and replacing the scales with something more hand filling, but I it might be better to trade it for something that's more practical.
Although I haven't handled a RAT, the sheath looks good, and the handle looks more functional. It's thinner, and I like FFG blades. Not sure I want to deal with the potential rusting of 1095 though and don't care for coated blades.
IMO, both the RC-3 and the 201 are a bit small for a fixed blade. Might as well go with a medium size folder of which I own several. A good bit of the RC-3 blade is choil, which doesn't do any cutting. The length of the RC-4 makes more sense for a fixed blade, but it's on the thick side for a blade of this length for pure cutting performance.
Let me know if you have any particular questions about the 201.