What do you know? They do work. I sent them in about two weeks ago and today I got two Best Buy gift cards worth the purchase price of the phones.
Since I sent in the base of an expandable set and they're our only phones I had to buy a replacement set before I sent in the old ones. It has talking caller ID which is a little creepy. The new set with 4 handsets only cost as much as the original base and one handset. So I still have two handsets I can sell on eBay.
Now I have to go back to Best Buy and convince them to let me use the gift cards to pay for something already purchased and refund the money on my credit cards.
So two thumbs up for Best Buy's product replacement plan!