I've used the first one on a mirrorless & it's no good at all. It moves inside & since my lens have zoom, it might spoil it & the photo that comes out may be blocked at certain part. I think you'll be better off with those hard plastic cover (like gopro's).

Well, if you're gonna use occasionally then it's ok. And perhaps its a better fit for your type of camera than mine.

Yeah & your lens is a zoom so it moves so you gotta have certain gap when it's retracted. Hence, there's loose space in front of the lens & that's why the position of the camera in the jacket will move. That's why if you can find those GoPro like waterproof hard plastic covering is better.

Err, as I wrote, if your camera is not fitly housed it might moves & your shots will be partially blocked. And mine have a tendency to float as it's not meant to be submerged. I think the latter is the most important aspect for you.