I would pick the rear discharge if you have a choice, seems to spread the grass a lot wider than the side discharge.
This is with my 24hp JD-770 with my 60" Sitrex rear discharge mower,
Normally I use 1st high when mowing but have to drop it to 4th low in the higher greener grass as I can't mow the area until late May or early June if I'm lucky so the grass get pretty high and if I don't want to sink to my axle. I have half wet soggy and half dry field and it does fine in the dryer taller grass but have to reduce the speed in the higher greener area, it will strain the old belts a bit in the taller green grass if the blades aren't sharp. Once it drys out then I can cut normally.
I bought at the same time as my JD-770 from a JD dealer 28 years ago and I haven't even changed a belt yet. I only cut around 3 acres or so but when I built my house it was raw land. They say it will cut up to 2 inch trees or so. I didn't try it but have definitely chewed up at least that size tree limbs.
I have rebuilt a wheel spindle or two, had a couple of trees jump out at me.