I agree with Vairom. If you create near-to-complex patches you will be sampling some of the parts to wav before working further. It's not really a problem for me, but it has to suit into your workflow... the biggest problem for me was when I failed to discover that I maxed out the TI, so I spend much time wondering why some times a note was played fine and other times it wasn't played at all. Then I started sampling the parts, and all is fine.
4 parts is a bit limited for me as I tend to fill up with a lot of strange sounds. This is also countered by sampling parts and exchanging them with new patches. The difficulty in doing this is saving the individual automation for each track. This can be done by midi, but since snow doesn't send out midi for its knobs in sequecer mode, this is somwhat problematic (but not impossible; you just assign another midi controller to send CC's to the synth stuff the soft knobs control).
Having 5 knobs to work with is fine for me since I seldom automate more in my tracks, and doesn't need more for playing live
About the samplers: I think that most samplers will do just fine for any style (I create Minimal/Progressive-like psytrance)´

) I use NI battery for drums myself (single drums, not loops), I'm used to work with Reason's ReDrum, which I actually like better, but I got tired of Rewirering.