I have a small lawn business (around 10 lawns) all of them about 1/3 acre. I was originally thinking about a walkbehind but went to my local dealer today and saw a 36'' hustler fastrack ztr. It has a 16hp Kohler Courage engine, and is supposed to be used for heavy duty residential/ light commercial applications. It looked like a pretty tough machine but I was wondering if I could get any opinions on this? How long would it last mowing what i mow?