@rbringh looking at a PIM/POH/whatever, it looks like RPM is only really changed during run-up to exercise the prop, and during cruise to reduce noise at mostly negligible impact on all other parameters. As long as you change Np slowly, it doesn't have a large impact on overall torque in the sim, but quick changes will do something. There's also a torque limiter at work when you aren't in 850 Mode that makes everything but torque regulate to remain safe, and in 850 Mode where the limiter is inactive, I really don't know what's even going on.
A footnote on Np in a performance table (all tables are made for 2000 RPM...):
Propeller RPM utilization between 1600 and 2000 RPM is possible without changing performance. Display the TRQ indicated in table with Np = 2000 RPM, then reduce Np without exceeding 121.4 % TRQ.
That pretty much looks a bit like leaning, but for noise, and some Socata Magic.