I have an old Kryptonite "kryptolok" u-lock and a NY chain.
I bought the New York Chain after I reposessed several abandoned bikes in my old apartment building. I bought a $4 drill bit and some tri-flow-- killed two "kryptoloks" with about five minutes of drilling. In short, I realized how ****ty my own lock was.
The NY chain is what I use for my Voodoo Bokor (geared). I love the bike. I'd hate to lose it...(I've even had dreams about chasing down a theif and beating him up with my wheel...)
Anyhow, I still use the kryptolok for my singlespeed. Nothing on it is terribly expensive or irreplaceable. I'd be livid if it were stolen, but the chances are relatively slim in my town. There are many more valuable bikes out there.