OK. Looks like I am going against the flow here. I have a JD 950 with 27 PTO hp, which I believe is very nearly what the 4310 has. I can generally mow my pasture running in 2 high, or even 3 high if the grass is not too high. It is true that if I let it get a foot or so tall and if it is really green and heavy, I do have to slow down to 1H, or even 4L if it is too bad. However, the time mowing slower than 2H is probably less than 10%. Having the extra foot during the other 90% really shortens my mowing time.
As was mentioned, tall, heavy, green grass is the main problem. Brush is not a problem. When I first bought the property, there was weeds taller than the hood of the tractor. I mowed thru those in 2H with no problem. But those were weeds so tall they had smothered out the grass.
