I have a Hobie 18, and I single-hand it all the time.
I crewed for a 10 year-old skipper at the Viento Fiesta this weekend, and we had a blast! In light winds, and with a 45 pound skipper, we were able to keep with the Tigers and 20's at least part of the time. The boat is a lot like a mid 70's american car- It moves along at a pretty good clip, but nothing happens all that quickly. In 5 years I have yet to flip the thing without trying, and I do a lot of cowboy-single-handed hull flying out on the wire. It is very easy to control, and when you are done you can sail it up on the beach and put it away wet!
You should definately check us out at Hobie fleet 2- I have had the same experience as Eric, they (or I guess we) are a great bunch of folks who love to sail and camp and eat. We have events scheduled all summer throughout Northen California and Nevada.