Go for it. You can never have too many wheels.

However, you probably won't be able to tell the difference. Yeah, maybe the first ride, but that's all in your head. I'd like to see a blind study, where somebody puts on a set of wheels, either your current wheels or the new wheels, and you're not allowed to look down to see which they are, and you try to guess just by riding. I think a lot of "experts" will get on a new bike and marvel at how "responsive" it is, how it "just leaps with every push of the pedals," when all it is is the new chain running on clean new cogs. If you ever want to really improve the performance of your current bike, just replace the chain & cassette. It will ride like new.

I think it makes more sense to have a set of heavy beater wheels that you don't mind trashing. Because you'll tend to ride these more aggressively, they will make you a better rider (you won't be holding back in fear of damaging the wheels, you won't mind riding in the rain or over bad roads, etc.). Also, because they're heavier, they will make you stronger and faster, especially when you put on the lighter wheels for the really important events.

Luis