I think the right thing to do in that case is report the failure and the customer service experience you had in dealing with it. I've had companies that I recommend despite an initial failure because the customer service experience in correcting it was excellent, and companies I don't recommend whose product worked relatively well but when the inevitable happened their customer support was sorely lacking.
As a consumer I don't get to buy a unit that the company hand picked and inspected with extra fervor to ensure that it's perfect, I get to buy one off of the shelf. So when I'm reading a review I want to know what the off the shelf experience is. If I read a review that gave the company "a fair shot" by ignoring the broken unit and reviewing the replacement I'd feel lied to.