Thanks for the replies!
Just some thoughts. I understand that the draft control was intended for soil engaging implements. However, I've talked to a number of old-timers over the years and they all told me the same thing, that it works just as well for cutters, that's the way they use it, and that has been my experience. If I just use the position control, when I go over a hump the cutter rides up in the air, and if I go through a depression it presses into the ground. The only way to effectively use it is to constantly keep my hand on the position control, lifting and lowering to try to keep it at the same height, which is very tedious when mowing for several hours.
I have found that, at least with the previous mower with the rigid upper link, with the draft response set to fast, the draft control works perfectly at keeping the cutter at exactly the preset height, whatever the terrain. I'll give it a try with the position control, assuming that the floating upper link is intended to allow the mower to tilt in order to compensate for terrain. But I have to say I'm inclined to modify the upper link attachment to make a rigid connection, since it has worked so well in the past. I'll post the results.