Longevity is largely dependent on install and how good you are with maintenance (filter changes). We had a pump in here a month or so ago that the owned claimed to have 200k miles on. He sent it in just to be checked out, not because he was having problems. When we took it apart, the wear plates had very little wear and the performance was hardly any different than the test results we had on hand from when that particular pump was new. If you don't follow the instructions (mainly concerning inlet line size) and you don't keep up with filter changes, the life expectancy will be much less. Follow the install directions and there's no reason not to expect long pump life.
The current Velocity manifold systems are low pressure versions. The 200gph can be made to be adjustible with an add-on regulator, but not much above 25psi. It's not going to hurt the pump to try to run it up higher, it just won't be very efficient. The housing/rotor/veins on the pumps we use on the current Velocity systems were designed to be efficient at lower pressures. We have inline pumps that are good for over 100psi, but we are still working on packaging versions of those pumps into a manifold style system like the Velocity 100/200. The high pressure technology is there for us, and has been for some time (we got our start in EFI gas fuel systems years ago)- it's the manifold packaging that we are working on now. The pump itself will be largely unchanged from one of our many gas pumps.