I've been dabbling with ZBrush for a while and have now installed the upgrade to version 3. Have not Modo ... installed (Trial) Mudbox, tried it, deinstalled it.
I'm no expert, but ZBrush is amazing ... I've subdivided objects up to 14 mio polys and it handles that without any problem. But beware ... ZBrush is addictive

... it's easy to just lose yourself sculpting something. And yes, it is a lot of FUN !
BTW ... kudos for the people who use Blender (although I primarily use Lightwave, I've started playing with it a while ago) ... I just want to pay my respect to people who use a free software (that isn't a big name, yet) rather than obtaining some illegal copy of 3DMax or whatever. (Sorry for the rambling ... it was something I just had to get off my chest).Cheers,
Andreas