I agree with your opinion as one of the reason for not to many review out there; few sites do reviews of pro cards doesn't mean there is none and for me AnandTech, and Tom's Hardware review is enough but they both doesn't have one.
unless the manufacturer is confident about their ability to do a proper test they won't send any.I remember reading a crap review of w9000 from legit review not a long time ago.
Can I take that as agree with my opinion; because Nvidia knew that if they will review K5000 now they will give it a disappoint reviews that could effect a buyer decision, so they don't send a sample to review it, and keep pushing buyer with their good reputation.
Poor Amd they are really hungry for Pro support to effect buyers, so they just send a sample for them even if they knew that they could give it a bad review, and then leave it for smartness of a buyer to catch the good review that will help support their decision.