Brian,

I did some experiments a while back with Moi to XSI, in Nurbs format, and it wasnt pretty. Like Michael said, their Nurbs support is ancient compared to modern tools.

For me, one of the major strengths of Nurbs, is the flawless booleans. XSI doesnt even support Nurbs booleans!!!!

XSI does have the best MentalRay integration, very nice construction history (which Modo needs badly), and some mature animation tools...but that's about it IMO.

-TS-