In the area around Zurich itself my opinion is that Sailing is pretty much a joke. There are plenty of boats that go out and sit on the lake in pretty much no wind. There are lakes over here that get a reasonably consistent breeze during the summer so something light with a huge sail area could be fun. Something like a skiff, Int 14 or any of the new breed of fast trapeze boats would be fun. As far as racing them is concerned I don't know where there are good fleets but I have occasionally seen races in Urnersee, and regularly see some fleet racing in Silvaplana.

In my opinion (In the past I have raced both boats and windsurfers) in terms of racing, formula windsurfing and a high performance boat will offer similar challenges. Technically Formula windsurfing will be a touch more difficult then Sailing especially since you already know how to sail and have yet to learn how to windsurf. But once you get to a certain level the tactics etc will be exactly the same.

I suspect however that if you learn to windsurf you may prefer to get involved in other aspects of the sport other then Formula windsurfing. Here in Switzerland they have a series of Races (not sure how many) for Formula windsurfing but I don't know how well subscribed it is. Either way you will need a car, but in terms of storage it will be easier to to store your formula gear then a boat.

Oh... If you decide to go with Formula windsurfing... Don't buy a Formula board to learn on. They are relatively technical to sail and easy to damage. You will learn much quicker and have much more fun learning on something a touch tuned down.

If you need any more info just let me know and I'll see what I can do.