I have U Locks on our remaining bikes now. U Locks are better than cables and it looks like they are about equal to good quality hardened steel chains with big locks. I still think the best deterrent is to just have a crappy looking bike and lock it up better than the rest of the bikes on the rack. This is a work in progress for us still while we are in an apartment with outdoor, secluded bike storage.
On our walk home today I saw this mangled U Lock that reminded me that anything can be broken if you want it badly enough.