to me, xsi is one hell of a package, i have the demo cd for version 2 and its pretty good, the only reason im not using it more is cos my monitor is too small for it, but im gettin a new system soon

i think the main reason maya is chosen over XSI by many people is cos with maya, there are more tutorials and more forums to learn from (like this one) whereas XSI doesnt have many, and also because of the price, softimage products used to be quite expensive, and maya was pretty good when XSI first came out, but now, i dont thinks its a case of maya standards slipping, i think its more a case of XSI advancing so quickly, i mean, between versions 1.5 and 3, XSI has had integrated a compositor, nurbs and subd modelling has greatly improved, workflow is also much faster with improved interface and hotkeys. A|W dont release enough updates, or enough IN their updates to keep all maya users happy, whereas softimage xsi contains many improvements and new technologies in all their upgrades so far