Don't really know much about the disc machines, as I got out of the hay bidness about 10 years ago. I grew up with Allis-Chalmers tractors and attachments. I ran a 9 foot Allis sickle mower from the time I could drive the tractor. If you had a sharp sickle, you could mow anything. Dad had a Shadle sickle sharpener at the shop and I disremember how many stones I wore out on that thing, but boxes of them. I still have my anvil made from a chunk of RR rail, my 13/64" punch, and rivet set. Snuff cans worked well to hold rivets and an old ammo box to hold it all worked nice. The thing I really liked about the Allis mower was there was no pitman stick to mess with...that thing would mow straight up or straight down.
We had an old 16 foot 620 Hesston swather that I ran for years, and then we updated to a 16 foot 6610, but we ALWAYS did the 1st cutting of alfalfa with the Allis, just to speed up the drying time. Only thing I know about the disc machines is that the fields look pretty ragged when you are done cutting compared to what they look like when you are done mowing them.
Another thing that amazes me is it seems like all anybody knows anymore is top-serrated bolt on sickle sections. Then they wonder why they have problems cutting prairie hay, especially wiregrass. I could rivet on a new section everybit as fast as you could bolt one on, and the riveted section would be tighter than the bolted on one. We had quite a collection of sickles, and had probably 10 with all smooth sections....you could cut ANYTHING with those. We had 1 that was top-serrated, that was strictly for alfalfa or sometimes cane. Under-serrated sections worked pretty good for a lot of crops, but the smooth sectioned sickles were my favorite. That was another winter job, repairing all the sickles, rebuilding them if necessary, and making sure they were all sharp and ready for the next season. We still have boxes and boxes of Herschel sections for about any mower that was in use from 40 years ago and later.