I'm happy with the decision* to support the XSIdot format, but only because i own a Ess. license, and a LW3D license which works with PointOven nice with XSI.(I still love to work with procedurals in LW for baking.)
But the Mod. Tool should it do it for 0$.
Here are some Video Tus for Free, they have commercial Training too.
http://www.digitaltutors.com/digital_tutors/video_category.php?vcat=xsibas
The only hard thing in XSI is to get behind the Application paradigm, after that it's just another DCC App.(View from a longtime LW User.) And most functions are well tought out.
There are many tutorials out there for XSI(or to say 5 years ago it was a way harder to learn it.)
I hate 3dsmax for two reasons 1. it is a way to pricey for a single user(or modder), and it's like a dinosaur, autodesk should rewrite it.(a long time ago imo.)
Compare it to XSI Foundation(arround 500 bucks) you should see it has the most bang for bucks. ( http://www.softimage.com/products/foundation/ )
But, anyway there free tools out there.
Anyway happy modding!