At 290 lbs you will be underweight for the Hobie 20. Most of the 20' cats are better suited for teams at 350 lbs or better.
I disagree with this statement. The H20 ideal weight to sail is 315lbs. You aren't too far from that weight. You would have to carry some weight for a while but it would be a good boat to get going fast on.
Since an F18 I'm guessing is out of your price range. 8-12K? I would like to know what area you are from so that I have more info to go on. I always recommend getting the boat that the other hot sailors in the area are sailing and then comming up to speed with their help.
The 5.8 is also an excellent choice that can be had reasonably. Also if Hobie 16's are being raced in your area I would recommend that.
Mike Hill
www.stlouiscats.com