I’ve always wanted to give that a try with the angle grinder but don’t have a spare kryptonite U lock to sacrifice.
I do have an old kryptonite chain with disc lock that an old roommate left behind. Lost the keys years ago and could sorta use the chain.
Maybe I’ll take a shot at cutting it off when the snow is gone and I can do it in the yard.
FWIW I think that a good chain and lock is harder to defeat than the U lock.