Lets say I was to hand everyone $4000 and said buy what ever you want! who would purchase the new mac pro?
I wouldn't! anyone else?
Second question Who would buy the new mac pro without the hand out?
Nope I wouldn't. I have an '07 Mac Pro v1.1 that I upgraded myself from two dual core (5130 I think) @2.66 to two quad core (5355) @2.66 and added a 3-drive RAID-0 and some RAM.
I'm under the impression that there just will NOT be any user interface speed increase AT ALL in the new mac. Rendering and multi-stream video editing might be a tad faster but almost every kind of CAD work, or userish editing will be the same. The kicker is that all new, it cost me less than $3k in all.
So in my case you're asking me if I would pay an extra 1K (and probably more) for the same system but with slightly faster rendering (1.5x faster). And the answer is....
Nope!
Now if the either the user experience were sped up significantly or if the rendering were >2.x times the speed then yes, I would think about it. When both conditions are true and prices are < $3,500 then I will buy one.