The X910BT writeup in the Crutchfield Catalog states:

"You'll control your system with the crisp and detailed 5.8" WVGA-resolution touchscreen, plus use voice commands for functions such as selecting navigation destinations, choosing albums or playlists on your iPod, or calling contacts on your phone with the built-in Bluetooth." - Page 8, Crutchfield Late Summer 2009 Catalog

If the F series let you control nav with your voice, I definitely missed something in the manual.

Likely a typo. And the F series did not support voice control for nav. There is also nothing in the manual for the X series that discusses voice control for nav.

the new Z unit allows you to use voice to select destinations. Pioneer has a video of it on their website. I do not believe any other series allows this. The F series def does not though.

It'd be interesting to see if Crutchfield would let you swap the X910 (if you order from the catalog) for the Z110 for falsely advertised features.

If not, Crutchfield has one of the best return policies anyway