If reading a review of the newest vendor's product, it is only fair to give the performance of the competitor's similar generation release. If there are strong availability/price concerns (eg generation N+1 is triple the cost of generation N) those should be noted as to why not performing the most appropriate apples-to-apples comparison.

Calculating performance / dollar is an entirely different exercise (though valuable, and rare is it the newest generation that hits the sweet spot).