Jupiter said..
Whether you need many boards to match the conditions is entirely up to you really. If you have the cash, then it is entirely your business to own as many as you wished. However, I doubt it will make you a better windsurfer though. It is time on the water.
True newer gear doesn't make you a better windsurfer, you could argue riding challenging gear makes you better. But new gear can make you windsurf better perhaps?
I noticed this effect with some of my newer gear and how much more forgiving they are. Bit like the increased sweet spot modern tennis raquets have over the older counterparts. Sure Robby and co could sail their high level on most anything, but for the average Joe, new gear can make up to a degree.
As for having fun, I'd have just as much fun on my older gear as I do now, so no real difference there.
I actually still sail regular on old gear, it's the sails I have upgraded and the some of my boards.
I still get out on this gear regular.
Mistral Equipe - 1989 model
Mistral IMCO 1990 model and sail
Protech 258 wave board 1996
Protech Z-26 slalom board 2001
Protech Sean Ordonez edition 1998