My R65 was carried away in the dark of the night once, with the fork locked.
When it was recovered by the police, the thieves kept the Tracy fairing, managed to get the worthless OEM battery (after a struggle, I'm sure!) and the sidecovers got lost along the way. Picked up a few scratches, too.
But there was no black market for a hot BMW in Indianapolis in those pre internet days, so it was quickly found in an alley somewhere.
But mostly I quit using my fork lock because I grew weary of picking up the bike after dumping it in the parking lot.
If you do use it, get a extra key blank with a ribbon that says "Remove Before Flight", to put in while it is locked.