I am in no way trying to bad-mouth Kohler, just passing along info I've received. I'd venture to guess there are Kaw's out there that are hard to start as well.
You're right. When I bought my mower, the Kawasaki engine was a considerable upgrade, if I recall correctly. Any manufacturer is bound to put out a problem-child from time to time. Mine is about 11-12 years old now and even though it seems to have lost a little umph, it still starts and runs pretty good.