Yes, PC 3200 will work...
There is a note about this if you search the Intel support site pages. As far as I have found, 2 GB will run on this motherboard, but it must be SPD (serial presence detect) DDR S DRAM unbuffered, non-ECC, suspend to RAM, X 16 double sided is not supported, low density type, 184 pin, 2.5 volt only.
There is some dandy PC 3200 high speed memory available nowdays, in matched sets.
Your question was:
"Documentation (see below) says the Intel D845GEBV2/D845PESV supports up to 2GB of RAM, but then, it goes on to say that 1GB sticks of PC2700 have not been 'validated' for use, despite the board being designed with those parameters in mind."
My response is "yes" from personal experience. i cannot, however, verify that PC3200 works, but it would be worth a try. i've also just learned that this board is upgradable to a 280mhz cpu, not that it would be worth the time and expense, but more so to again point out just how advanced this board was for its day.