Anything on a pto I run at the operating rpm for the pto, in my case rear PTO is 540 (about 2380 engine) RPM, mid-mount PTO is 2500 RPM, matching the engine.
For steady heavy work otherwise, like with the backhoe, I go with the tractor "operating RPM" on my B2650HSD is 2500. That's the RPM where...