I'm running a 72" VX4 and have yet to see the first clump, but as we all know, different cutting areas bring about different results. I run the 72" at top speed when cutting a large percentage of the time and it leaves a very good cut, absolutely nothing left standing. The only thing I see that would concern people on high end lawns is the longer clippings, but this is something that does not bother me in the least, and that is due to the fact they are scattered so thinly and uniformly. I hear many people talk about it being impossible to cut grass at 13 to 14 mph, not true in my area, and as a matter of fact when I was cutting Saturday I caught myself on more than one occasion trying to push the steering levers more forward in an attempt to get additional speed. That would be hard for most to comprehend, a 15 mph ground speed mower, and the operator is trying to make it move faster. People must remember, with deck drag and blade spin you are probably only cutting in the 13 mph range. I had a friend stop by the other day wanting to operate the 35/72 but I had no grass left to cut. He got on the mower and took off what looked like a rocket due to me never seeing anyone run the machine but me. I looked at the speed he was running and said to myself, watching a mower moving at that speed is extremely hard for me to believe it could cut grass and do a good job. The mower looked to be flying, faster than a normal person would believe grass could be cut without leaving any standing, but a mower running with the deck not touching and blades not turning is much faster than one actually cutting.