If you're thinking about racing I think it really comes down to crew weight. The minimum weight for the F-18 and the N-20 are not very different but the weight the boat can carry through various wind ranges are very different. I happen to tip the scales around 215 to 220, If I race a f-18 I need really light crew in anything but "blowin'" conditions to be competitive. The N-20 will carry a heavier weight in lighter conditions better in my opinion. That's why I bought the N-20. Conversely if you and your crew are light go with the F-18 as the N-20 will get to be a real handful in a real blow. I have raced on both and they are both great platforms, I would look at your combined racing weight to decide. Also if you are not sure that you would have consistant crew go with the F-18 or depending on your weight look at the Blade 16. You can race it one up with main and spin or two up with main, jib, and spin.