XSI doesn't have the hiearchical (sp?) mode to there subd's unlike Maya, but there are soooo much faster and easier to use

The price puts a lot of people off XSI and its particles aren't as good as Maya's, but then Maya's particles aren't as good as Houdini's

in my eyes, Maya is the best software when it is coupled with Renderman which is how most of the big studios use it, but that takes the cost up to XSI (roughly £4500 for Maya unlimited and £6500 for Renderman)

the only software with true subd's is renderman anyway, every other software still has to tesselate them into triangles which renderman doesn't