Kc, you just go ahead and think it's half assed, and you'll miss the boat. I've built more engines than you'll ever own, and any builder will tell you head work is foremost in performance. This includes decking. If you're capable, do the math and see how very little needs milled to raise C/R a significant amount. Consider what 1mm will do. A machine shop will charge only about $50 to do too. I'd never stop at just a deck job though. The things that can be done to the head while it's off are endless. It's quick it's easy and it works.

Valve timing will retard ever so slightly, but not enough to concern yourself with. Unless you're going for the all out perfect tune, in which case you'd be going for adjustble pulleys anyway and be degreeing the cams in exactly. Valve to piston clearance will be no different than with the same C/R pistons either. The exception here being flat tops vs. reliefs. With so little being shaved, I'd be very surprised if the temp increase would even be measureable.

I've got to say grinding, no matter how it's done, is a bad idea. Spend the money for the mill work to ensure it comes out perfectly flat and at the proper tolerance. Also, have the chamber volumes matched at the very least. If you can spend a little more, get 5 angle seats too.

I'm not saying everyone should run out and deck their head without doing some engineering and planning, but until someone offers a forged flat top piston and high strength rods to go with them, a piston swap is not the best way to raise C/R. In fact, it just may be half assed.