I wouldn't be surprised if they couldn't be picked apart easily for smaller prints as you state. To design a 300mm lens is many orders of magnitude more difficult and expensive at F/2.8 than at F/5.8, which is over 2 stops slower.
That said, the "S" in "SQF" (the type of table those attachment are) stands for "subjective"
and it is certainly not an MTF table.
Making conclusions based on one review alone (and then one criterion such as the vacuous term "IQ") is not a great idea although it will certainly make people happier depending on their circumstances (i.e. if a lens they own checks out well!).
I did try the 16-50 and did not like it, with or without a review to affirm or disprove my conclusions.
Originally posted by dylansalt Great article.
Unfortunately we all need some objective data to start with before purchasing a new lens.
I know inherently that the 300 will produce excellent IQ and will be the superior lens i.e focussing speed,low light etc
But in terms of the review here the 55-300 will (in pics up to A4) give me the same IQ (relative to my seeing eyes) as the more expensive 300.
Just as much as people owning the 16-50 will say that it gives way better IQ than the kit lens - I simply can't see it in the pictures - thus I would say that the 55-300 must be an incredible little lens for the money (but taking it's known slow auto focusing speed out of the equation)
D