NOTE: I do not do any tilling or haying, so I would think 2wd is ok for those applications since most of my farming buddies use 2wd for that sort of stuff, they just have bigger tractors.
You have never done it, but make the statment 2wd is OK. If you just want OK then 2wd is OK for everything. I have a friend I help with tillage and hay, tillage you just can't compair, it's night and day. 2wd is still at a disadvantage in hay. In hilly areas when going up and down, or even across a slope unless you weight the tractor down it's not hard to get pushed around when baling. This is really true going down hill, the weight is over the front end and off the rear. We have 2 - 100 hp tractors we use, the 4wd is set up much lighter. The 2wd has both tires filled and cast weight. The 4wd has none on the rear, going up the hills the 2wd due to this weight we have to drop the ground speed to pull the hill. Even mowing, now we can mow as soon as the rain stops and not tear up our fields. Where the 2wd we needed to wait a day or we would be leaving marks in the hay lot. The 2wd mowing up hill you will see from the lug marks the tires are slipping. Since we got the 4wd the 2wd just does tedding, raking and hauling wagons when we are putting up hay.
Most farmers around here now are buying 4wd in every size. The advantages are just too great. 30 years ago or so 4wd was an after thought add on unit's that were poorly designed. Today the 4wd is designed into the machines at the start. To get the same pull from a 2wd my experience has been you need to add about 20% more Hp and a lot of weight.