My FD75 seems to have less issues then the 740hd with pushing in the sickle overlap area or pushing and dragging under the head. Macdon is a lot less weight then JD, might be important on the 9770.
To make the floating cutterbar work well I think it needs an airbar, which is more $ and more maintenance, and makes it much harder to see when conditions are dusty or at night.
Picking up lodged small grains is pretty easy with a macdon, JD wouldn't work at all.
Macdon gets my vote.