I own a 2011 Z920a and I am thrilled with it. Monday night I cut my lawn that was over 7"s tall, down to 3.5, and I did it at normal speed. The cut was perfect and you would have thought I only took a little off. Since I have started using this machine, people have commented that my lawn looks so nice. I believe its the nice flat cut because I am not even fertilizing it this year.
I was a bit nervous when I first got it since it is the bottom of the Z900's for power, but there has never been a time I would have wished for more power.
A suspension seat would be nice, but other than that, I am more than thrilled.