2005 Intrepid 31 Wa reprop from 16 x 19 P to 16 x 21 P 4 blade

I have a 2005 Intrepid 31 WA, with optional large fuel tank, with Verado 300’s. with my current Merc Entertia Eco stainless steel 3 blade 16 x 19 P props, I run about 32 mph at 4000 RPM. I need to be around 36 to 3700 RPM to hang be on the step.
Some mechanic said i should try the Mercury Bravo 1 Offshore 4 blade stainless props. He said it would have me on the step at a lower RPM and lower my cruising RPM to be at the same 32 MPH.
I do not want to buy new props and find “it is not so”
Comments but would prefer comments from experience.
Many Thanks. Marvin