Alright, I managed to get my Droid X overclocked last night. Initial testing is not looking very promising.
I wasn't able to get Quadrant to even do a full run without rebooting the phone at 1.1Ghz. Looks like Motorola has this thing clocked surprisingly close to its frequency limit on stock voltages out of the box unless I ended up with a bad sample. Keep in mind that this was with stock voltages, though, so not all hope is lost yet. I didn't get this working until about 4am so I didn't have a chance to mess with the voltages since I had work this morning.
I'll work on it some more tonight and report back with additional findings.