The manufacturers talk about the top speed of their zero mowers, but I'm wondering just how fast one can really mow, given a typical set of conditions. Just for jollies, I ran my exmark metro (36", 12.5 Kawasaki) in fifth gear for a bit today to see how cleanly it would cut. The deck bounced a bit, which does not bode well for a clean cut. A few of my jobs have pretty flat lawns, but most have at least a little roll to the terrain that seems to eliminate the possibility of going faster than the 6.2 mph (or even THAT fast--fourth gear was okay, but that isn't 6.2 mph) advertised as the top speed for the Metro. Next year, I'll get a bigger mower, but I'm wondering if the better speed of zeroes is really of any use. Any opinions?