What I don't get though, is that if ferriday say they can machine the head to loose some compression ratio following too many skims, that would suggest they also do something with the valve seats (sink them further in the head), otherwise, as you say, their whole procedure would be pointless.
As much as I trust Karl implicitely, I would have thought a little machining would be less stressful to the head, but I am no specialist and could easily be talking out of my backside here.
Maybe I'll give ferriday a call after all and report back.