They should move a given amount of water at a variable pressure (within reason) so if anything you'd be creating higher pressures at the pump with a restriction.
I don't mind about higher pressure at the pump (if it won't break stuff) just the puck and if water debit would be adequate by restricting flow to obtain 135psi/9bar.
I'm wondering if I can take the outline from a vibe pump and install a valve as a flow regulator and a gauge right after it to measure adjustments/restriction. I'm almost positive it will be adjustable to bar pressure but the effects of doing it are what I have no idea about.
hampered water volume at the puck
Back pressure at the pump causing a mechanical failure
It might work
I'm unsure...
Meanwhile all the OPV is doing is diverting the excess pressure HOWEVER the by product is a loss of water volume at the puck that is diverted back to the reservoir. It's this bit that has me wondering. The only advantage I see is that it allows the pump to run full output rather than have to wait for flow to pass a regulator valve inline. That may be VERY important or not...I'm clueless.