I have the Nikon 500F4E ED FL and like to hand-hold so did not even consider the 600FL. Ordered the battery grip and the TC 1.4 which should still be fast AF/great IQ and give me 840mm. I shoot primarily on a very wide river so the birds can be very far away. do not do any video as of yet, but would be nice to know I have the capability. Yeah, seems Canon has the edge with video on the R5 but being a Nikon shooter and now adding the Sony, the last thing I need is to add a 3rd system LOL