This is probably a lot more to do with the fact that Maya performs faster on Linux, than it being a noticeable performance improvement related to the graphics driver. Its not the only app where this is the case, Houdini is also a tad faster on Linux than it is on windows. Linux is.. well... faster on the whole isn't it ? This may also probably the case for minecraft too. Also, I don't think Maya officially supports ATi cards, just saying that cos YMMV depending on the generation of ATi card too. Basically, there are too many vagaries to make anything approaching a meaningful comparison here. The only thing to do would be to run graphics based benchmarks on both platforms, assuming that the benchmarks are coded in the same way too of course. But they've already done that, hence the % figures in this articles title.
As for the argument that CAD applications give the graphics cards more work, I really don't see how thats the case, a 3D viewport is just a 3D viewport after all. However, yeah, the processing in the backend to maintain the surfaces accuracy (is the term Type A surfaces ?), yep, thats a lot more hardcore than it is for 3D animation/modelling/rendering applications. But, and I'm interested to know if this if its wrong and someonecan explain it to me, drawing the 3D representation on screen isn't any much more of an effort for a CAD app than it is for something like Maya.