Bingo.Keep in mind that the new tractors (for the most part) use diesel fuel to regen so they use more fuel than the pre- tier 4 engines. My M's are real frugal on fuel but PTO load (depending on implement and power requirement) causes consumption to go up. never tracked it, it gets low I pump in more.
One of the major reasons I went with a 2 speed (540-1000 rpm) pto. The power requirements on my hay tools is such that I can afford to run the engines at reduced rpm and power output as well as lower fuel consumption and still have enough pto output for the hay tools to perform correctly.
I see no point in running the engine at rated rpm to achieve 540 when I can run the engine at basically 1/3 rated rpm to achieve 540 with the 1000 rpm 21 spline output. Only drawback that I can see is you need a 21-6 spline adapter to run 6 spline implements.
One thing I did have to add was a 12 volt auxillary fan to the AC condenser under the hood to enhance the airflow through it at reduced engine rpm. There wasn't sufficient airflow through the ac condenser, the intercooler and the radiator combined to provide sufficient heat exchange, especially at the AC condenser which on my units is the farthest from the radiator fan.
Interestingly, when I owned a 5030 HSTC cab model, I also had air flow issues through the ac condenser, the HST cooler and the radiator and I had to add rubber deflectors to channel the air flow and an auxillary 12 volt cooling fan as well.
I have EPTO on my M9960 and nearly always use it when mowing. Operating the engine at around 1,750 RPM results in about 600 PTO RPM.
Saves fuel and revolutions.
My gear drive 9960 uses considerably less fuel to mow the same parcels with a 7' cutter than does my L6060 HST with a 6' cutter. Much less. It also does so in less time. HSTs are convenient but inefficient.
SDT