Yes, I would say that 5 out of the 6 crashes I've had over the past 10-15 years have been due to wake turbulence. What usually gets me is the wind is blowing when the flight starts. Even if it's just enough to knock out the wake turbulence. But usually, sometime during the flight, it goes dead calm and I don't compensate and sure enough, I hit the wake turbulence, usually exiting a square turn near the gound, and whoops! Plane suddenly drops 4 feet and I was only 3 and a half feet off the ground. Sigh... Did in my USA-1 and last year my Novi. I've really got to pay more attention to conditions when it's like that.