Hi Chilled,

It's been a while singe I've used the poly-subD route for modelling. As far as I can remember you get strange non converting results with non manifolds and tris I.E non quads. The history may also build up and cause problems depening on the changes.

Personally I would now advise using purely polys and using the smooth mesh preview for smoother iterations of the model for previewing the smooth poly (as I'm sure thats what your going to render in)

Jays the best for sub-d's as he knows the whole shizazle when it comes to modeling, NURBS, Polys and Subs.

Cheers

Steve