I like to do sail aways on my boats and have done a few of them; combined with some distance racing. My experience on the F16 (despite still being somewhat limited) is that the speed of the boat is not a problem. As someone else already said, the best I-20 crew and worst I-20 are seperated by several hours. We must all realize that a very good I-20 crew and a very good F16 (or F18) crew WILL NOT be seperated by more than 30 minutes after 10 hours of sailing. The issue is far more between good and bad crews that between 20 and 16 foot boats. It is not like teh worst I-20 crew is hours behind the best I-20 and that the best 16 foot crew is yet again hours behind the worst I-20 crew.
Having said this I still don't think that the F16 is a particulary good platform for a Tybee 500. The significant difference between a 20 ft boat and small boat like the F16 is not the ability to perform OR surviving but rather the demand made on the concentration of the 16 foot crew. It is undeniable that a shorter hulled boat takes more concentration to make it perform optimally. It is more sensitive to steerage and control than a bigger and longer boat. I'm sure an F16 can handle the Tybee 500 legs and the atlantic ocean. These boats over a very wide range of control and are easily depowered. HOWEVER, I'm not that certain that its crews can sustain the required concentration for so many long legs after one another. The first days will be alright but then fatique and possibly lack of sleep will deteriorate the level of concentration that these short boats require. A 20 ft is just easier to sail in this respect.
Last year I did a distance comparable to Texel. One that went 11 miles out to sea as well. We had big wind and big swell with nasty short chop on top of it. The boat handled all without a complaint; we (the crew) however were beat by the end of the race (3 hours). The feel of agility and quick responsiveness is great on any bouy race course, but it becomes tiring in any serious long distance race.
My advice to any short hulled sailor is to become one with the boat before attempting a long distance with rough conditions on these short hulled boats. You must know the boat so well that it doesn't require much effort from you to sail/race it. On these boats you must beware that fatique will grid down your concentrations and that a vicious cicle is lurking. Loss of concentration due to fatigue => makign mistakes requiring excessive energy to correct => more fatigue => more loss of concentration => etc.
Now I really don't believe doing a distance race on a 16 foot (or F16) is dangerous or impossible, but one does need to really prepare himself for it and understand the drawbacks of a short hulled design. Compare it to doing the canonball run in a Covette or a boosted mini-cooper. Both are equally fast and in principle equally safe but the mini-cooper with its short wheel base is more demanding (nervous) to drive at full potential for long periods of time.
Wouter