Very similar experience here; bought myself a Kinesis for home and one for work (I'm sure they'd have paid for it, but I couldn't be bothered). It was quite possibly the best $600 I've ever spent. I don't mouse enough to have yet bothered with the trackball, but perhaps I'll get one to try it out.

The only downside I've found (other than cost, which is a non-issue IMO) is that you get very used to the keyboard and now when I go to a conference room or someplace else with normal keyboards, I might as well be typing with my elbows.