Now, the question is do I go for a new C-11 or do I go for a blemished or demo C-12? Personally I think it makes more sense to use the C 12 and be future proof. In my case they would put on whatever I choose and purchase.
I know you're asking for dlleno's opinion, but see the report on my positive experience using the C-12 clamp. I'd heard about lever clamps being affected by slight changes in the geometry of the plates, but I'm surprised that RRS' can't be adjusted. In any case, I've only used knob clamps. They're a bit slower to use, but you know for sure when they're tight and it's very easy to make quick adjustments as you slide the plate or rail while keeping some friction.