It would be a waste, unfortunately.
If one had a slower system (Pentium, Pentium II-class) they could be worth it to slap together a cheap and dirty system.
And to think these things were going for $299 or so three years ago, but 3 years is a long time in this business. I bought a BestData Arcade FX II V2 SLI two years ago for $250 for both. I even bought the V2 Stealth coolers for both of them and oc'd them to 103 Mhz clock.
Look what one can get for that much Jack nowadays! I still use it b/c at least its fill rate is still decent and comparable to a V3 3500. It can still run games but if you have a GF (anything), I wouldn't recommend it. You'd just be wasting an extra PCI slot.
A V2 SLI is also great for the Ultra HLE w/c is an N64 emulator. It can run Zelda 64, Mario 64, StarFox 64 like no real N64 could! Of course, you don't want to do that right?
The author is making the next version of Ultra HLE to work with OpenGl, so I may soon retire these bad boys.
If one stills plays Tomb Raider (1), I found out that the 3D-accelerated *.exe version can run only on a V1 or V2 board but not on a V3. I've searched everywhere and no executable will do it.
A lot of people new to computers ask 'why' add-on 3D cards were ever introduced in the first place. They ask if the 2D/3D boards back then were any good. Now that's something to talk about.
Well, maybe not really.