Gilo, The boats are pretty similar in speed, the biggest difference is with the F18 you must always race with crew, no Uni option (unless your home club allows it). With the F16, you have the option of racing without crew. So if you will always be racing with crew, you can probably pick up a used F18 cheaper, especially if there are alot of them in your area looking to upgrade to the "newest" F18. But if you think you might not have regular crew for every race, and you may be hualing that boat up and down the beach alone sometimes, the 170lb. lighter F16 might be a better fit for you. I think you will be compettive without a handicap vs. F18's once you get some time on the boat.