I bought the 6' drum from SFI. Getting used to it. It's heavy and takes a little heft to get it changed from the stow to operate position but not all that bad. Getting the PTO out of the way for that is a bit of a pain, but tolerable.
It is very smooth and quiet considering the drums are turning at a very high speed. Cuts nice and as stated will cut just as fast as you choose to drive. I have mine set up for the 3" cutting height and this is just right. Cuts good and smooth, but doesn't scalp and leaves a nice stubble for regrowth.
Does a good job following ditches, pool/pond dams, and uneven terrain....within reason...I mean the tilt of the drums from the tractor position is like 15 degrees up or down. The 6' weighs a little over 900# and when in the operate position and drums are not on the ground, a light front end tractor might have some left front wheel lifting concerns. I have 4wd with FEL and it works fine. It doesn't take a lot of hp to run. My 57 pto is more than ample.
6' isn't very wide but I have a small place and it does fine in the tight spots where a larger machine would cause me problems. I have my tractor wheelbase set up for 6' also so I just line up on the windrow from the previous cut and get a nice smooth cut.
I shopped for something to cut hay without having to use a sickle or haybine. Had looked at quite few used discs but were more than I wanted to pay and I didn't like all the moving parts....my choice. My disc runs off 3 parallel drive belts, has an oil sump for the gearbox that drives the drums, and has 3 zerks...2 year warranty. Can't beat that, for me anyway.
Would I do it again? Yes, in a heartbeat.
HTH,
Mark