I think the 9.5mm limit is only if doing two drives, if you are replacing the original drive you should be able to get away with a taller one if you want something like the WDC 2GB drive.
Fast options are (all 9.5mm)
Seagate Momentus XT (8Gb SSD with 1TB HD in hybrid package)
HGST Travelstar 2.5-Inch 1TB 7200RPM
Or just a little smaller, but cheap and a proven one: WD Scorpio Black 750Gb.
I think the 9.5mm limit is only if doing two drives, if you are replacing the original drive you should be able to get away with a taller one if you want something like the WDC 2GB drive.
I've tried a single 12.5 mm drive once and could not do it, because I read somewhere you could. Perhaps if you make mods on the caddy. I think from memory the problem was the wifi grill fitting properly and the sata ribbon did not sit well on the logic board. Otherwise I would suggest sticking to 9.5 or 7 mm 2.5" drives.