Interesting thoughts here guys....

Yes, all aircraft (both pistons and turbines) have redundant fuel pumps (well, redundant EVERYTHING), and it's for good reason.

Is 3-5 PSI enough here? I had figured 30+ PSI? The other question is how much flow is required?

From a performance aspect, I'd think feeding the injection pump straight from an electric, pressure fuel pump would be an advantage, but while one could easily just remove the vacuum lift pump from the equation, I'm guessing that leaving the SOV just hanging there with no fuel flow through it would trigger codes.

Ideally, you'd have sufficient pressure, with sufficient flow, that it would require a return line and a regulator.

Here's an interesting article I came across, which discusses this (and more):

OM606 fuel supply issues