I also own a 2012 snapper pro s150xt 48" with the FX series kawasaki engine. Bought mine new in 2012. Says the engine is a 20 horse, but kawasaki rates it as a 19. It is a very well built machine. Yes the mower will cut at 10 mph as claimed. I mow a little over 4 acres and as long as I mow every week I can mow at full speed with a great cut. My lawn is fairly smooth with a few rough spots. If your lawn is very rough you may not be able to stay in the seat. Hydro gear claims that the zt5400 pumps will actually reach speeds up to 18 mph, but I don't think my mower would cut great at that speed. Very impressed with the power of the Kawi engine. I was a little concerned that it may be under powered when I first bought it because the other engine option was a Briggs 25 horse, but it handles hills and tall grass very well. Not great with clover, but i cut the lower part of my lawn yesterday after 4 days of heavy rains with no problems. Grass was so wet the ground squished when I walked on it. Couldn't mow at top speed due to the height of the grass, but was still able to mow 5mph. Could never have mowed that grass with my old tractor mower. I have numerous trees in my yard and can mow the whole thing in about 2.5 hours. Before I bought the place My uncle and aunt mowed it with a husqvarna 60" zero turn residential and a 54" cub cadet tractor and it took them 3 hours.