"Maybe I will have to try out the demo of XSI to see what it looks likt (although I hope it doesn't end up like the kind of learning curve I got trying out Maya PLE :))." Weeeelllll... there's going to be a learning curve involved to say the least. If you've never worked in an XSI interface environment before, you'll be lost. Also, the renderer (Mental Ray) is quite complex and deep. It's a professional-grade rendering engine that has been used before in many movies and television works. It's a production-proven renderer, and it's a tad more complex than the Vue renderer ahem. ;-) So yeah, you'll need a lot more time to learn it. But as with all things worth doing, the effort will pay off in the end. If you're going to try and compare Vue's GI/HDRI capability to what's capable of Mental Ray in XSI, then you'll find there's NO comparison. Mental Ray is one of the absolute best professional-level GI rendering engines in the industry, and one of the ONLY ones that can actually USE GI in a production environment (Brazil and Vray being among the others, but that's a whole different ballgame too). But as I mentioned, Mental Ray will be quite a beast to tame. Good luck. ;-)

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.