I won't argue the valid point you made about the slip clutches vs shear bolts. I've just completed mowing 35 acres with a Woods 6' XT172 rotary cutter. The grass was so high in some spots that my H started to bog down so I finished with the 730 diesel. I didn't bust a single grade 2 shear bolt using a 60 hp tractor driving a 40 hp pto gearbox. This guy is looking for a nice, affordable, apparently light duty rotary cutter. I recommended a Woods cutter and relayed my experience. My neigbor was using a rotary cutter with a slip clutch (I can't recall the brand name) and he was too lazy to get off the tractor to investigate why his clutch was slipping. Turns out he had inadvertently sucked up some wire into the mower and it was binding up. The slip clutch overheated, melted the plastic clutch shield and ignited the brush clippings and residue on top of the mower deck. Cost him a gob of money to get the mower fixed, and nearly burned up his field. May not have happened with a shear bolt.
I know that sometimes the shear bolt can be a pain but if I have to do that much heavy cutting, I'll use a mower that is big enough to do the job. The bigger mowers with heavier gearboxes use harder shear bolts and can subsequently withstand greater shocks when cutting heavier material.
I don't have anything against slip clutches, but it's going to cost that much more for the mower. I certainly don't recommend using shear bolts with greater hardness grades than what's recommended by the manufacturer to avoid damaging the costly-to-replace gearbox or my tractors. In the end, you'll get what you pay for. It all depends on what you're going to cut with it and how you cut with it.
Thanks for your input on your experience with mowers Haas. This guy will hopefully read these posts and come to an informed decision on what he needs for whatever mowing jobs he wants to do.