RE: Sail quiver: One or more manufacturers?
Well.....I've been in the have lots of sails camp, moved to the minimalist sails camp, and am now finding myself erring back to specialist pairings. Even to the point of one-board one-sail at the lighter end of the wind range. I guess I'm an example of the grass being greener on the other side of the fence, and in years I'll be cutting back on my sail quiver!
I do think you want to carefully pick the sails to match the board, and the size the board manufacturer recommends may not be a perfect fit with the sail's rated size. Test drives would be the best option.
....and don't forget to experiment with the fin - sail pairing, as well. I do think that some sail-board-fin combos are like they were made for each other.