Most of my area I can do at 6 MPH, some is nice enough to run at 8 MPH... I'm going to try to get more of it smooth enough to do all of it at 8 MPH...
My older L130 couldn't run faster than about 6 mph and it couldn't mulch much faster than 4 mph. I am hoping to find out how fast I can mow with the new X749, it has a top speed of 8.5 mph but until I try it I won't know what the cut will look like.
I should add that I used a landplane grader to smooth out the lawn areas at home so speed and smoothness isn't a problem.
Here is a pic of the lawn area with the landplane and harrow I built for smoothing lawns.