Well, first off, stock compression in an all motor car is not any where near enough, and the simple equation of compression = power, is just not enough of an explanation.

The reasoning behind bumping up your compression, is that it allows for the ussage of larger cams, giving the motor more power to push such a large cam profile, and to be totaly honest 11.1:1 really isn't cutting it if you really want to make any power. Compression by it self, does give you power, but not a sufficient amount to go tearing apart your motor for it.

To answer your question, I personally would stray away from milling your head, it permenantly sets off your timing, or at least to some degree and also moves the whole combustion chamber closer to the pistons. As far as valve to piston clearance with a head gasket, using the Mugen or Spoon ones you see out there will be no problem at all, you just need to adjust the timing accordingly, which goes for any time you change compression. Even after milling your head, you should have no clearance problems, just don't go more then like the thirty thousandths you mentioned, otherwise on pump gas, you'll be pinging all over the place. I'd go with a nice set of forged pistons, it allows you to run at higher tolerances with regards to tensile strength, heat, and detonation, where milling your head, you're still running on stock internals. Though, you wouldn't need to buy a new head if you mill it and wanted to go back, you could just buy a thicker head gasket, it's still a process that isn't easily taken back.

The bottom like is, that thirty thousandths you mill your head, is a good cheap way to put your compression up to about 11.8:1, and this way you don't have some of the problems commonly associated with thinner head gaskets, such as blowing out, and being less heat tolerant. Another thing, if you just want a thinner head gasket, just cut out the center of a stock one, it accoplishes the same thing, just be careful when installing it, as you need to remove the rivets to cut out the center.

lastly, higher compression does not = more maintenence, properly tuned, it wouldn't require any more or less maintenence then your stock compression.

In any case, Later!!!!

Aj