I'm thinking of a CCF Stainless frame for IDPA.
The Vanek trigger is legal?
The CCF frame, to the best of my knowledge, isn't legal in IDPA at all. Or USPSA Production. If it is IDPA legal, it would surely move you from SSP into ESP, where you'd want to add a magwell and a couple of other widgets to remain competitive.
Which of the Vanek triggers is the best?
The Grand Master or do I send it in and let Vanek do his magic?
I run the "Trigger kit #1" - the $120ish drop-in kit, and I'm very happy with it. The trigger you get when you ship it to him is supposed to be even better, but I'm VERY happy with mine, it's very light, 100% reliable, and I can swap it from gun to gun without issues.
I don't know if Charile does anything else in the GM kit besides adding a ligthweight striker, but you can buy a Lightning Strike lightened steel striker for $50, FYI.
I run the drop-in with a lightened striker, and I swapped out the LWD 3.5 connector he uses for a severly polished stock 5-lb connector. This took every trace of sponginess (and there was very little compared to the stock gun) out of the trigger. It's got a very crisp break, and is STILL lighter than a stock 34/35's trigger - I'd estimate it at about 3 pounds.