I can think of one good reason not to mix POST and GET - it often doesn't work[!]

Good point! I was a bit weary of that, but the second set of scripts I have up there does prove that they can coexist peacefully.

I had intended to use them both for separation of run mode control and transfer of data, i.e. use the GET variables only for "out" functions like: display page X. Then use the POST variables for input, which (in most cases) would be parsed and inserted into a database. Plus the forms I have for the full project will have some pretty hefty data entry, so I might be brushing up against the GET size limit.