I spoke with a Pioneer Nav Tech a few days ago about the maximum capacities and was told that indeed the SD is limited to 8GB but that the USB was working presently up to 32GB and may be better later.
He couldn't confirm that the capacity will eventually be increased up to 250GB like previous models, or that it will be upgradable through the SD card, only that it might be possible in the future, maybe.
I am personally more interested in using a large capacity Ipod so that I can take advantage of the voice recognition system. I hope that it works as well as they advertise. My F90B