Hi cildean,
Not a BX owner myself... not even orange.
For PTO driven applications manufacturers will always refer to the 540 (or 1000) standard for the implement... the results of using attachments at lower than 540 PTO rpm may produce satisfactory results for you... may save fuel, wear & tear, and lower noise as well...

some feel it will destroy your tractor and/or implements to run lower...
the "DO YOU MOW AT 540 RPM" thread shows how varied opinions are on this matter...
I operate at the rpm that gives me results I want without bogging the motor down... low for my spreader (sand in winter on parking lot--NOT a field), medium for the logging winch (unless I want more speed & oomph hauling back), and about 85% recommended speed for the rotary cutter, unless there are big obstacles ahead.
On all ground engaging & loader work, I try to stay ~20-25% higher rpm's than the torque peak on my engine, so the motor has some room to gain torque if/when it begins to bog down, plus the motor isn't screaming in my ear all day unnecessarily. I only crank it up for higher ground speed.
I would shoot for results on your PTO stuff, and keeping just ahead of your torque curve for all else... I'm sure kubota has it listed in your manual somewhere.
Only my opinion, of course!

Good luck & have fun!
