I just want to add a comment about dealing with salespeople... as Harvey said, you don't want to get them to haul out a dozen mics on a Saturday aft when the store is busy... but OTOH, the salespeople are there to serve you and sell you something - it is, after all, their job to let you try the products and find one that is right for you - which means demo'ing it.
Somewhere, somehow, people got it into their heads that we shouldn't bug the salespeople, as if we were interrupting their "important work" so they can sell you something! Well - their "important work" IS to sell you something, so they should be accommodating you, and not the other way around....
And if they don't want to play ball, I'm the first one to tell them that I'm taking my business across the street, where they DO accommodate proper demo'ing or I remind them of the many on-line retailers that offer a demo and return policy.... they usually change their tune pretty quick after hearing that.
Bruce