About commenting on what one hasn't heard - I think it's ok to have an idea based the rest. It would be silly to comment about the sound, of course, but I can still read and watch reviews, specs and such to have a somewhat informed opinion.
Re the never-ending overpricing debate -I pulled and compared data for a lot of speakers and among a few things, one is very obvious: you usually get what you pay for. With a "freakonomics" approach, I'd say that very few brands are overpriced, in the sense that some party in the distribution chain is "overpaid" disproportionately.