I think it's just ezr to use the same brand becuz any decent manufacturer has already matched the specs so that their tweeters blend w/ their mids in terms of freq response, power handling, etc.

If u want to make your own matches (maybe to find something that matches your taste better than the standard offerings), even across brands, and u have the skill to do so, then go for it. But that seems like more of an audiophile thing to do, rather than something the average enthusiast would do.