I have the ATI Radeon HD 4870 512M and Autodesk Softimage 7.5 64bit version.
For anyone looking for a collection of referenced benchmarks between the 2009 Mac Pro, here are a few initial links and images. Seems we have seen fragmented benchmarks, leading to a considerable amount of confusion and anxiety.
If anyone has additional thoughts / benchmarks, link them or add the graphs here. Overall, the midrange octo 2.26 has some distinct advantages, all cost considerations aside.

All charts below (grey and red) courtesy of Rob at barefeats:
http://barefeats.com/images09/neh04_ae.gif
http://barefeats.com/images09/neh04_ps.gif
http://barefeats.com/images09/neh04_com.gif
http://barefeats.com/images09/neh06_mot.gif
http://barefeats.com/images09/neh06_ima.gif
http://barefeats.com/images09/neh03_cin.gif
http://barefeats.com/images09/neh03_g32.gif
http://barefeats.com/images09/neh03_g64.gif
Digital Arts review, March 18, 2009. Mac Pro 2.26
This one shows an advantage to the 2.8 by a 3% gain in the single render category yet an advantage to the 2.26 in the multi render category of 6%.
http://tesselator.gpmod.com/Images/_Equipment_n_Tutorials/Cinebench10_Numbers.jpg



