No matter what cat is selected for the olympics the platform will dictate the competitive weight range.

Using one of the Formula rule is a bad idea as it will have the effect of increasing the cost by a huge factor as each team/manufacturer will spend a fortune developing olympic proto boats

Using a one design from a formula class is also a bad idea: this has the possible effect of having the selected model take over the whole class, I believe that what happened with the Tornado in the past.

So what do you want in an olympic platform? Two crew, three sails, modern design, fast and spectacular. One design, ideally with boats provided for the event. So, what platform could fit these requirements?

16':

The venerable H16 with a spi is a possibility. Everyone knows what a H16 is, you can find one everywhere in the world, they are cheap and the class is used to provided boats for events. Downside: the NA class don't like the spi, the weight range is light light light, and albeit spectacular sometimes the H16 is technically a slow dinosaur.

Viper: As I said I don't like the idea, as the Viper is a F16

Spitfire: Nice boat, still evolving, but the weight range is too low IMHO.

18':

As I said before, bad idea to select a F18, even an older design. There are not a lot of 18 footer that are not F18 these days...

20':

Tornado one design: Known quantity, spectacular boat. But it looks dated with its pointy bows and centerboards. The best bet really to stay olympic.

Go to something new and exciting (Macca will like me know) like the Nacra F20. This boat is spectacular, extremely quick, highly technical and one design. Probably the same cost envelope as a Tornado.