Yes the texturing workflow in XSI is much, much MUCH more powerful than it was in Soft 3d. It take a little bit to get used to if you were at ease with the soft 3d texturing workflow, but everything you could do and more is there. The combination of the rendertree and a built-in shake-like compositor means that you can get more out of a direct render from softimage than any other package, by far.
Ed Harris's videos on texturing and rendering using XSI do a good job of bridging the gap between soft3d and xsi, showing you how you would have performed basic tasks in Soft3d and then the new workflow to ge the same result in XSI.
So you may have a period of frustration until you get used to it. Particlarly missed is the renderball, you now perform a realtime render on your textured object itself or must make a proxy with standardized lighting etc.
Thats the downside. The upside is that the render tree is VERY powerful, and the average artist can do things which would have required custom written shaders previously. Also if you ever had to use rendermap, you will find that it is now a joy to use rather than a chore.
I still miss the shaderball tho.