RE: New Quiver of Sails - Help!
Here are my thoughts:
1) In this era of CAD programs, it is very very difficult for an experienced sailmaker to design a bad windsurfing sail. Therefore a premium price should be justified only by tangible differences such as superior materials (almost everybody use the same kind of materials depending on intended sail use), more sophistication (i. e. number of battens or cams or carbon tube battens...), better manufacturing; and, most of all, better useable performance vs. the competition.
That said, I think that NP premium price is totally unjustified, and even more.
2) One important issue is mast compatibility. Given you are choosing a sail quiver, be sure you use the proper masts and do the math including mast purchase.
3) The size spacing you are thinking at seems more or less OK to me. Things will be eased if you choose rangy sails.
4) Modern cammed sails are a breeze to use compared to older ones. If you mainly sail in moderate winds and flat water, you should definitely consider that option. By the way, such sails are the ones with the best wind range by far.
Here is my very personal pick for an uncomplicated, rangy, durable quiver: Ezzy Sails Wave LE 5.8, Infinity or Freeride 6.5 and 7.5 (but then the Saber would see little use).
It is difficult to pick sizes according to your desires without jumping from a manufacturer or sail line to another, which I would avoid in order to have the same kind of behaviour throughout the whole range.