I'll be echoing what others have said before me, but since I have tried both I guess I'll toss in my 2 cents. I have Volo Powers and my friend has quattros. He swears by his Quattros and I'm in love with my Volos. One dive we decided to switch, and let me tell you it's a world of difference. I could tell that the quattros are quality fins, but they really are power fins. They're significantly stiffer and harder to kick, but you definitely get more speed out of them. My volos on the other hand are more flexible, it's easier to kick, and while you don't get as much speed, it's still very good given how easy it is to kick. Plus the volos are excellent for minor manuvering adjustments ... it gives you superb flexibility for when that sea fan appears out of nowhere in front of you on a drift dive and you have very little space to work with to manuver around it.
So if you're a power swimmer and you want great acceleration, and you're not afraid of using those leg muscles then get the Quattros. If you like fins that are easy to kick with but give you decent speed and excellent mobility go with the volos. I've "chased" things in my volos before no problem, but it's just not going to have the same power and acceleration as the quattros. This shouldn't really be a hard decision for you, you're either one type of diver or you're the other.
Btw if you get the volos, definitly get the volo power. I've heard the original volos suck.
