I very rarely use the tractor in 4 wheel drive. About the only time is plowing snow or in very muddy conditions.
I have a kubota L4310 hydro it has absolutely no whine whatsoeverThat's normal. As you work it more the whine will get louder. Have you ever heard the squeal when you accidently held your car steering wheel against the stops?
Try using a lower range on the hills and/or increasing the RPMs slightly, whichever works best. After a while you will get a feel for what your tractor does and doesn't like, and gear it down accordingly.
My Kubota was so obnoxiously loud that it would drown out the sound of the engine, and I had to wear ear plugs underneath my ear muffs. When I serviced it I put in the Super UTSD or whatever Kubota calls it. They are really proud of the stuff and charge accordingly, but it quieted the transmission down considerably.
I have a MF 1754 that has been a lot of trouble. It was purchased new in 2018. The dealer has been less than helpful solving the tractors problem. My advice on a MF product would be to pressure the dealer early on to correct this problem you probably have. The tractor has a 5 year warranty. Above all things don’t let the dealer stall on the solution.I have a 2019 Massey Ferguson 1734E that has a very loud whine when operating. It has been doing this since it has been new. The dealer has been here several times and has checked fluid and hydro pressures. All seems to be good. The tractor has 65 hours on it and when I did the 50 hour fluid / filter changes all looked good. The dealer stated some have louder whines than others. Is this normal for HST???? This is my first HST tractor. The tractor does have a FEL which operates fine.