Don't know if the Gamma clamp has changed since when DD used it, but I have 2 Gamma clamps and an Eagnas clamp. The Eagnas clamp is extremely tight, almost too tight for my taste. I used to prefer it over the Gamma b/c it was obviously stronger.
But as I used them more and more I now prefer the Gamma. It's not hard to open which makes it much faster and enjoyable to use for me. It has also never slipped and I use it to start my mains and my crosses all the time (as well as to tighten knots).
I've had no issues with it collecting residue. I clean it regularly and it works very very well.
The only thing that Gamma could do better is make that diamond coating infused into the clamp instead of on a thin piece of metal that is then glued to the clamp.
Other than that though, it's a very good clamp and it works very very well.