We haven't been discussing the relative merits of the Sony vs Canon 100-400mm lenses. The discussion is about the the new Sony 200-600mm. If you do purchase the Sony 200-600mm then we would be interested to hear from you your first hand experience with the lens and its performance vs the Sony and Canon 100-400mm lenses.
You are right, discussion was not about merits of the Sony vs Canon 100-400mm lenses.
Discussion was what kind of performance could be expected from Sony 200-600mm lens at 600mm based on published MTF charts and initial reviews.
MTF charts shows that this lens expected to have approximately the same resolution power at 600mm as Canon 100-400mm at 400mm.
You told that you have little trust in simulated MTF charts based on MTF charts for lens from some other brands (for cheaper lenses) which had lower performance than claimed by MTF charts.
My response was that from my practical experince I do not see any reason not to trust Sony MTFs for the latest GM and G glass taking Sony and Canon 100-400mm glass (as i have and use both) as an example.
MTF charts show that they have almost identical performance and in real life I see practically the same, with Sony 100-400 GM performing a bit better on Sony bodies compared to adapted Canon lens. Most possibly Canon 100-400mm would be performing better on Canon high res bodies as each lens optimized for use on their native bodies.
All my latest Sony GM and G glass was performing up to expectations (per Sony published MTFs)
Based on my experience I do not see any reason to expect lower performance from 200-600 compared to what is expected from MTF charts, the only doubt what whould be QC and lens variance as lens production facilities will be in China.
I think we will see test results from Lensrentals and DXO some time later.
Now this Sony 200-600mm seems to be very attractive and affordable choice to be used on a7 and a9 bodies and and that could attract/bring more users from other brands to this camp. Also internal zoom is very handy feature, especially for long distance video use.
I still believe that Canon 200-600mm or similar lense at the similar price tag and the same or better performace could be very attractive for Canon users. It is not too late yet for that.
And yes, if I decide to buy this 200-600mm lens I could share my experience with this and comparison with 100-400. I usually do number of different tests initially to see if Iwant to keep new lens or return it back to the shop.