I wish I knew. I can tell you 6 ft is too big. Maybe my experience can help you decide.
My YM240 came with a Leinbach disc, 6 ft wide and 650+ lbs. Sixteen pans, 18-inch size I think.
The previous owner said he used it a couple of years in a flat, flood-irrigated walnut orchard but could never get it to dig in. Adding
ballast just caused wheelspin or stalled the tractor.
Here everything is on a slope and it's not suitable. It won't dig in plus I can't pull it uphill. I tried 125 lbs ballast on the front (shown here) then an additional 150 lbs on the back, and finally decided on no ballast to run at a reasonable ground speed. I've loaded the rear tires (and they are oversize 12.4x24) so I don't often lose traction but even in a low crawl gear it won't get down more than 3 inches after several passes. In the attached photo I've gone around the perimeter of my neighbor's side yard about 4 times and that short ground cover still hasn't been turned under.
Another neighbor, a real 3rd generation farmer, uses a big disc for orchard tilling. He looked at mine and said it is intended for smoothing after plowing with a much larger tractor.
Presently I have the upper link short to load the disc weight on the disc's front axle. (And on the tractor's drive axle to improve traction). The back pans just skim along to fill in the furrows. This will pull in H-3 downhill and H-2 uphill but its not cutting very deep.
I'm considering a rototiller.
Would anyone with a larger tractor like to buy this disc?