Typically when you are working your tractor hard with front end loader work, running in low range is preferable. Finish mowing and rotary mowing depending on grass height medium range is preferable. Regardless of hydrostatic or gear. Never heard any one running out of horse power in low range rather they are losing traction. Your operators manual will outline ranges and gear selection for noted equipment. Golden rule don’t lug a diesel select range down keep rpm’s up if working the tractor hard. One last passing thought pay attention to your radiator these smaller cubic diesels heat up fast under load. Keep screen clean and remember to change antifreeze per manufactures requirements. The pH level changes over time. Well maintained tractor will last you lifetime. I maintained Kioti for 17 years before I traded it for new cabbed tractor.I've loaded the heck out of my B2601 and never noticing lack of power uphill or otherwise. Loaded tires, box blade as ballast and bucket full of gravel or heavy load on forks no issues. I generally run in M and about 2200 RPM. I don't know how much extra weight is in your cab but that's the only difference I know of between the 2601 and the 2650.