As I’ve understood the reviews the “S” is better than the “C” regarding IQ, but the difference doesn’t seem big. (And some reviewers actually find the “C” slightly better at certain focal lengths.) My brief experience of the “C” version indicates good AF performance, and probably the “S” is even better (the “Sports” designation indicates that the “S” may have better AF performance).

Maybe the main difference between the versions is build quality. I had a look at the “S” version in a store and it seems really solid. That may be the main reason it weighs 50% more.

I believe both versions have their potential buyers, and for me the “C” version was the better choice. (For my needs the IQ difference just didn’t make up for the differences in weight and price.)

For sure I will go for more practicing, testing various apertures etc. For example I’m curious of how good it can perform at 600 mm under better circumstances, i.e. stopped down to f/8 on a tripod, but that will have to wait until the weekend.