Hey Lance, nice info you posted here.
I noticed the same thing w/ my K7, and my friends' K7s have the same problem. We bought those split scressn from focusingscreen.com, but we all feel the focusing is just a tad bit off. It's more obvious when using a fast lens as you addressed above.
I thought about taking out the stock shim and putting in a thinner one, but haven't given it a try yet. I might do so over the weekend. Needs to find a clean place w/ nobody moving around. W/ two little kids around, I can't do this at home