I've used a trial version of the capture one. At the time, I loved it.
However I obtained a copy of lightroom 3 (haven't got lr4 yet) and well, it flawlessly runs with photoshop (meaning you can export straight to cs5). From there you finish in photoshop, save it and lightroom picks it up again if you need to use lightroom to do one or two more things. THAT fact swayed me from capture one. Other than that, I'd propose that you should use whatever feels more natural to you.
I've used phocus too (hasselblad's program), didn't like it. It was ok, again one could probably get used to it, but it didn't grab me.