I mean, he's the guy I originally asked if he knew about any mainframe compilers that made use of access registers, so he already knows that there's at least one person that would like access register support. I myself wouldn't go so much for the larger memory models (since you aren't going to need non-flat addressing for the sole purpose of gaining extra address space with 64-bit addressing, and probably not with 31-bit addressing either), but would be mostly interested in seeing a small memory model (all pointers near by default) with support for explicitly declared far pointers, and for something like OpenWatcom based pointers (section 7.3.3 in the OW C Language Reference).