To substitute a "pro" level driver on a consumer card, and actually enable the pro functions typically (I know of no direct, unmodified swap that actually works and enables the pro options, but may be wrong) takes some modification of the drivers (an activity that is illegal as specified by the driver  licensing agreement). Both Nvidia and ATI have used identical hardware in both the consumer and pro cards, with on board ID setting hardware that enables the pro driver functions and the use of pro drivers.  3Dlabs has only "pro" cards, and makes some very fine OGL Cards.

For applications that use the high end OGL functions, the  "pro" cards are well worth the additional cost.  In some cases, such as using Quad Buffered Stereo, the performance of 3DLabs  cards typicaly is MUCH better than Nvidia or ATI (quad buffered stereo is not available in consumer cards). So it really depends on the software your using, and how Open GL is implemented, to determine if a "pro" card would make any real difference. 

In fact, for gamming, a pro card will actually have poorer performance than the "equivalant" consumer card.  My guess is that you will probably see very little difference between pro and consumer cards on Carrara, since it is aimed at the "pro-sumer".  For applications that take advantage of the high end OGL features (3DS Max, Maya, Etc.), you will definitely notice improved interactive 3D performance and image quality/realism.

__________________________________________________________

My Rendo Gallery ........ My DAZ3D Gallery ........... My DA Gallery ......