I think finish mowing is the most popular purpose for the mid-PTO. Some other uses would be a front rotary broom and snow blower. The bigger class III's really aren't great lawnmowers. Thus as you get up there in size/HP, the mid PTO's become scarce. Kubota eliminated (made them optional) them on the Grand L's, NH quits at the TC40, I think Kioti at the DK40. Most users of larger tractors will use an RFM.
Much more practical in larger tractors is the live and/or independent PTO. Independent activates with a lever or electrical switch independently of the clutch or transmission. Live PTO means it uses a dual clutch. Press the clutch 1/2 way down to shift or disengage the transmission, all the way to disengage the PTO. You feel the extra pressure on the pedal, so it's not really tricky. Either system is really OK, just what you like and want to pay for. The live is simpler and less expensive. What you don't want is a transmission driven PTO. If the rear wheels aren't turning, neither is your PTO. The other problem is the momentum from a rear implement, say bush hog blades, can keep pushing the tractor forward. IMHO, a shuttle shift and live PTO are the minimum requirements for any tractor using 3-PT implements and a loader.
Pacesetter