Marc Alhadeff posted the final 100-400mm GM lens review:
The FE100-400 GM OSS F4.5-F5.6 is a excellent lens that well deserve the G Master label
– It is very sharp from center to corner, at all focal lengths
– On the range 100-200mm it is neck to neck with the 70-200GM
– Its weight , handling and build construction are very good
– AF speed is very fast, and especially reliable when coupled with the A9
– It has beautiful blurry background effects between 200 and 400mm with a good bokeh
– It can without any issue ,support a TC1.4, keeping very high quality and a good handling
– The usage of the TC2.0 will be best with a sturdy tripod and good ball head
– In video, considering the very long focal length, a tripod or monopod is a must
Lens store links: [shopcountry 60806].