It's funny cause I have a '98 and a '96 Fox. The '96 has a delrin bolt tip with the venturi holes drilled right up to the bolt face where it meets the paintballs. I have to say my '96 is more accurate than my '98.
The '98 was my main marker back in the late 90's, back when I actually played paintball on a semi-regular basis. The bolt tip on my '98 broke off and I got it fixed ICD and they replaced it with an aluminum tip. The tip was one big hole and the venturi ports are located back near the end of the bolt, more like the bolt tip on the Cat series.
And if you ask me, I really think that having those venturi holes drilled right up against the bolt face makes a more accurate marker. I don't know why. I'd like to think it has something to do with the fluid dynamics of the burst of air hitting the paintball more evenly through those hole sections, but I could be way off.
I know that the Freestyle line has the venturi style holes right at the end of the bolt tip and I think the Freestyle is a darn accurate marker too.