I got no complaints with my onguard bulldog mini tc. It was only $20, half the weight of the kryptonites, and it's great for my little errands. It is not significantly weaker than a krypto; I'm pretty sure it'll still take power tools to defeat. Too small for leverage attacks. I did a lot of research on this and a while back that alanbikehouston guy gave it the thumbs up, and he seemed to know his ish. To me a krypto mini is not worth >3x as much. If I was locking my surly steamroller up all day everyday or something, I would however use a big ol' krypto chain or at least get a 2nd U.

As for the onguard keyhole I did read them being a little fishy for some people but you've just gotta be sure you don't turn the key until it's 100% inserted and the crossbar fully pressed in. If there's resistance, don't turn; pretty simple. Also I might get some graphite lock lube as a preventative, can't hurt.