For one thing each color gun is only 8bit for the tested graphics cards, and the programs used to test the cards listed wouldn't even begin to take advantage of some of the abilities of the Parhelia.
I'm fairly sure that at least the Radeon 9700 (Pro?) also uses 10 bits per channel. Parhelia may have been the
first consumer card to do so, but not the only one.
Matrox said themselves they were not trying to make a gaming card
Actually, that's exactly what they said they were trying to do.

But other than the "Surround Gaming" using the triple-head technology, they evidently failed with the Parhelia 512. It was slower than the competitors cards that it was supposed to supercede, it was more expensive, it doesn't support all DX9 features, and contrary to the usual expectations on Matrox stuff its image quality was not better, but in some instances even worse, than the competition at the time.
The older and way cheaper GeForce 4600 Ti beat it hands down and stomped all over its corpse in 3D/gaming performance back then, and since then we've already seen the even better Radeon 9700, and soon the GeForce FX.
If someone really needs three monitors in 3D intensive apps/games and has too much money, then I could possibly see a use for the Parhelia 512. The "pros" are probably better off with even more expensive "real" workstation graphics anyway.
Anyway, what good are graphics card reviews like these in an AmigaOS/MorphOS perspective, unless there are drivers for them and even half of their features are actually utilised in AOS/MOS, their 3D APIs and their apps/games?
Not to mention that the other hardware (mobo, CPU, RAM, AGP bus) that AOS/MOS will be running on will never be able to push a graphics card made after the rest of the hardware (2000-2001) over its limits.
I suggest to wait and see what drivers there will be and then loot the "vintage" or second hand market for cheap graphics cards. It's not like they'll become more expensive with time...

For now, one of the supported Radeons looks like the best buy for AOS4/MOS users.