Well, the battery was just about dead the other night, so continued attempts at SBFs just failed. I let the phone sit for about 36 hours and got the battery recharged before reattempting yet another SBF. The SBF completed successfully (again), and what do you know? The stupid thing decides it wants to boot up this time.
Honestly, I don't know what happened. All I did was let the phone sit for a long time with the battery left out and the SD card removed.
And now I'm back up and on nightly 9, ready to rock and roll.
It was a terrifying experience, though. While my X was down, I had to use my BlackBerry Storm. After experiencing the X, I have NO idea how in the **** I managed to use the Storm for two years.