I picked up the PPQ SF yesterday. I put 100-150 rounds through it just to try it out.
So far so good. The grips are "grippier" than the plastic PPQs but I like that. The weight difference is noticable. Particularly when shooting one handed or weak handed, that weight makes the gun more forgiving of less than perfect technique and follow through. It's just easier to keep the gun steady in one handed strings than with the lighter polymer gun.
The next step for me is to install an Apex trigger and mount and RMR. The RMR is because my eyes aren't what they used to be and the Apex is because I simply prefer the feel.