I haven't tried a ball bearing trem yet, but I will the moment I get the chance. They sound tempting.
Right now my fav trem is one they don't make anymore. It's a Kahler 2700 series "Killer." All hardened steel except for the fine tuner screws which are brass. Instead of the knife edge on the trem, it's on the posts which are really just heavy duty screws with a flat head. It's 50 cents to replace them at a local hardware store. Each saddle assembly can be adjusted for string width and string height without shims. You don't have to cut the ends off the strings or break out a hex wrench to loosen them(I modded mine so I do both though). Each string can be individually whammied up at least one tone if you tune up with the fine tuners set in the middle or higher. I can't help but love these Kahler fulcrums. I root for the underdog and the features are almost unbeatable.
This upcoming NAMM, Kahler is going to announce their new fulcrum trem finally. I've been hounding them for months about when, how much, can I buy a prototype if they aren't moving forward with it anymore, etc. Whammy J from Whammy World is a good guy I've dealt with a few times for trades and little parts and he said it has the option of either ball bearings OR a knife edge and the fine tuners are the smoothest thing he's ever used. He would not e-mail a pic. With the Floyd Patents gone or going, we're going to see a lot of great trems, but probably a lot of even cr@ppier units than we see now.