Does the 12:1 piston come with gaskets? It might be the same as a stock piston with a DRZe base gasket, only a little lighter. If it uses the Z's 3 piece base gasket and you put a DRZe base gasket in you would be around 13:1.
The DRZe valvesprings seem to work great. They are a double spring instead of a single. IMO I would go with these and save a little money.

With my current mods listed in sig (still has jetting issues). I have raced a raptor with a stage 1 hotcam and Yoshi pipe and beat him the whole race. I had a lot more top end then him. He does weigh about 60 lbs more then me.

With cams, pipe, airfilter W/O lid I raced a Yfz with a WB silencer. We were within a quad length the whole race.

Im very impressed with the way the Z has responded to each mod I have done.