I would not expect great optical performance, especially wide open and the aperture limitations are likely going to require higher ISO for some images. This makes such a purchase as unlikely, except when you consider two parameters, size and weight. This lens might be with you when carrying heavier, larger lenses is not possible, or desired. A good example would be travel photography where long telephoto isn’t central to what you are shooting. So, I don’t expect stellar optics, after all they didn’t even put it in the ‘G’ family, but it might still make it into my bag.
This may not hit my bag immediately. Or at all. I have several potential uses and no immediate need, actually. Several years ago, pre-adding ff, I added a 70-350 to use with my 18-135 and A6400, later A6700 - fitting in when the 200-600 was too big and too heavy which was a lot of the time. I added the 70-350, knowing it was aps-c but that the them available 70-300s and 100-400s weren't all that inspiring., for me. More recently having added ff, A7Riv then A7Rvi and 28-200 and 20-70, not necessarily in that order. The 50-300 is an interesting fit with the 20-70 by numbers and the 70-300s and prior 100-400s or 50-400, well, still big or heavy or expensive or not much better a fit.
Perhaps in competition with the 50-300 replace the 70-350? Most of the time, I use my 28-200. Far more often than the 20-70. So 100-xxx may aggravate the 20-70 crossover to a second lens.for urban where I go back and forth over 70mm a lot but a nice fit with the 28-200 for the less frequent longer stuff.
I'm not sure how the TCs and "too slow" apertures will play together and it may go different for the lower res (not A7R/A7CR) users.
