Still haven't ordered ti4200 caps, but I have upgraded the p3 733 to p3 1000. Not really worth it, some say. Let's 3dmark99 that, I say.
733 with Rage: 4709/11073
1000 with Rage: 4901/14083
So a <5pct gpu increase, and an expected 3000 cpu increase. Conclusion: good for cpu tasks, rather tiny difference for Rage gpu tasks.
733 with voodoo2 12mb SLI: 4392/10965
1000 with voodoo2 12mb SLI: 4796/13968
So a 10pct increase on the Voodi, bringing them close to the Rage (100pt less instead of 300).
Conclusion the upgrade from 733 to 1000, which costs less than $20, gives a good cpu boost and adds another stage to your Voodoo rocket. For other gpu's, the difference is a lot smaller.
Note that 3dmark99 is not the whole story as it isn't focussing on Glide afaik.
I haven't checked voodoo temps yet, but with open case and all the fans it felt cool during 3dmark.