Yes your right Danny, I was just using the spur gear as an example of the differences compared to a geroter. The Roots style is just a variation of a spur gear with a different gear profile, but same pumping principles. And I think your showing your age here a bit Danny
peterson and pretty much all other mainstream US manufacturers have been making either spur or roots style for the best part of the last ten years!
JP, The OPI looks a hell of a lot better on paper/pictures than the other offerings. But, who knows?? try one and find out, or if you want peace of mind as to what your getting go with something like a Peterson or Dailey (the dailey's really are extremely well made)
The oil squirters just feed off the blocks oiling system, no need to feed them direct from the pump if that's what you were thinking?
As for weather the pump will have enough capacity to feed them, it would be very unlikely any decent pump will be not capable, and if you found pressure dropping off at high revs/temp then you can adjust the pump speed to compensate, providing that doesn't lead to cavitation.
Basically pump speed is a trade off between oil flow demand, cavitation and efficiency (you only want to run it as fast as you need)
So it's a totally tunable system. Pretty much every off the shelf pump will cater for all but the most extreme setups as they are all bigger than they need to be. some manufacturers will offer custom sized stages, but they are more suited to huge drag motors with massive oil demands.
Llew