advice on mac pro purchase for running rhino3d or magics

[i don't know]

I use Rhino3d to design and Magics from Materialise to prepare these designs for output to RP machines. I also do a lot of rendering. I have been looking over the new Mac Pro configurations and am having trouble deciding to go for the new SAS drives or not. Has anyone read of any downsides other than the added expense and mandatory Raid drive? I was considering the Quadro FX card, unless there is something in the market not offered by Mac, that can be added after purchase from Mac. Some of the files i use are huge, so i want to purchase on the strong side.

Any suggestions?

Well.