TYVM Falcon! It's nice to see a colleague of sorts here!
Whether nVidia Quadro or AMD/ATI FireGL is the better choice, really boils down to which price range you are looking at. Although I have no personal experience with the two lines, I read a very good article comparing them all (CPU Magazine July 08 -- Pro Graphic Battle Royale). The only two cards to score the highest of the lot (4.5 of 5 stars) were the nVidia Quadro FX 3700 and AMD FireGL V7700. The two cards performed similarly, but seems to me the Quadro edged out the FireGL in most tests. The biggest difference between the two is the price: Quadro FX 3700 at $1599 and the FireGL V7700 at $1099. That's a $500 (30%) difference for roughly the same performance. This adds up real fast if you need 10 of them!
In the lower end, the Quadro FX 570 is only $199, where the cheapest AMD/ATI card they tested was the FireGL V7600 at $999. Apples and oranges.
So, a couple of big questions before I can take a stand, since it really boils down to: which exact models you are looking at? How many systems will you be assembling? In other words, budget.
If you need 5-10 systems in the end, I would suggest building only two at first. Identical in every way, except one has a Quadro the other has a FireGL. Let a couple of the architects use a system for a couple weeks, then swap them into the other system for two more weeks. Then, consult with them to see which of the two they prefered and why. Now you can go ahead and make more of the systems using the prefered vid card and maybe a few other tweaks to the component list (that you discovered when building and setup of the first two). If you only need 2-5 systems then this may be a little difficult to pull off, and would be best if you could return for exchange, the video card you decide against. A good supplier should not have a problem with this, when he is getting several sales out of the deal in the end.
If you are looking at the lower end cards, it seems nVidia is the only player in town. In the mid range $1000+, it seems the FireGL is a huge bargin, providing the users like it. In the highest range $1900 - $3000, it seems there is little benefit for the massive price jump.
Here is a quick scan of the article results table:
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