The old 10w30 vs 20w50

For the OP, one of the benefits of a lighter oil is better cooling of internal engine parts. With 25 psi hot idle pressure, I would not worry about going down a grade level in hot viscosity. But, the hot viscority of a blended base 10W30 is going to be a lot lower than a group III base 5W50, so I would not be surprised if the hot idle oil pressure goes down more than 5 psi.