Thank you, everyone, for your answers! And thanks, Michael, for putting my mind at ease. I'm using MoI on a PC (haven't modelled anything on a Mac for years), but it seems to be really solid, and as others have pointed out, very easy to use. MoI, so far, appears to be a great companion to Modo, especially for those objects which are just a little too tricky to model in SubD. OK, so I'll end up using Poly and SubD objects together, but I'm happy with that.