I love this program! It's literally just like taking a ball of clay and shaping, stretching, and reworking it into what ever you want. As for poly-count, yes, it does put a lot of demand on that, but there are options for setting it to limit the poly-creation, plus the use of the "poly-reduction tool" is very nice. I wish we had such a tool in anim8or.... Then one could more easily rework subdivided things selectively.
I haven't worked with Sculptris heavily yet, but my only "downer" so far is that it won't work on my mini-machine... but it looks like it is demanding of memory anyway, so no surprises there. Anim8or is likewise a "small in size but big in demands" program as far as memory usage and all goes.
There are some really cool results shown on their forum, with their various competitions, challenges, etc.
I think that using both Anim8or and Sculptris could prove very useful. Of course, Sculptris is based wholly on triangles, and I know how critical folks are of that...
I also saw that the program developer made some sort of texturing program to use in conjunction with Sculptris. I haven't checked it out fully to know if it is compatible with anim8or exports, but that might be something to look into soon, as well.