Using Nikon SB-800 remotely in FP high sync mode?

Just out of curiosity, is it possible to use the SB-800 (or 600) remotely in FP high sync mode with a D300? I tried it using the built-in flash on my D300 but when I set the Custom Setting E1 flash-sync to 1/320 (Auto FP) I couldn't get a shutter over 1/320 unless I connect the SC-17 sync cord (yes I made sure Custom E3 was set to commander and that the SB-800 was in remote mode and that I had the Channel and Group set correctly both on camera and flash)... I sometimes find that the cord gets in the way and it would be nice to simply leave it in my bag when I have my flash mounted on a bracket.

Well I got it figured out... When choosing the settings in Custom Setting E3, the on-camera flash needs to be OFF, which is indicated by two dashes (--). The on-camera flash will still fire the necessary flash to trigger the remote flash, however the output from the on-camera flash is minuscule and should not contribute to the overall exposure of the image (I tested the output and it is considerably less than when it is manually set to 1/128 power). I was originally trying it with the on-camera flash set to M @ 1/128 power, and because the on-camera flash isn't FP high sync capable, it overrides and limits the shutter speed to 1/320 even when FP mode is selected and suitable remote flash is being used.

Very interesting, good research. Now, how are you planning to use this capability?

Eh, I might use it out in the field when I have my flash on a bracket (i.e. when using a telephoto on a gimbal tripod head). I find that I sometimes get annoyed by the sync cord (yes I know it's minor) so it might be nice to leave the cord behind. In the least, it will allow some flexibility if I ever forget to bring a sync cord.