I’d recommend that you make the switch, I use a 6D as well and the A7s blows it away. For run and gun shooting it is great in that you can switch between crop and full frame mode so you can have two different focal lengths, but added to that, if you’re shooting in just 1080, you can digitally crop in 2x while shooting as the A7s has a 4k sensor. So you can use a 35mm prime in full frame, knock it into crop mode and you have a 50mm, and if needed crop in 2x and you have a 100mm, combine it with your 70-200 and you’ve got a serious focal range for a days shooting, the 2x still looks good too! This is something i just stumbled across as it isn’t advertised or talked about very much – but it is really handy sometimes. But beware, it is not as user friendly as the mark3 – a bit fiddly, shit screen, and its size is uncomfortable to hold, therefore a half-cage to make the handle bigger and an external screen is something i would suggest. Essay over haha!