Hi my name is Mal Collins, and I new to this forum, I live in Neerim Sth. Victoria. I have just switched over from Nikon after 30 years, the reports I have read on the A series swayed me, looking for some memorable times with the A7r111a + 200=600 G lens.
Yeah, a lot of reviews say the a7r cameras aren't the greatest for wildlife, I think because the time it takes to process high res photos means the speed of continuous shooting is compromised.
Dust on the sensor of any mirrorless camera is more common than SLT or DSLR cameras because they lack the mirror that helps protect the sensor (SLT are susceptible to dust on the mirror that can show up - and the mirror is fragile). However, careful changing of lenses, regular use of in camera sensor cleaning or blowing with a puffer - lens off, camera facing down - helps a lot. When a sensor gets too dirty for these steps to work properly, I've been surprised how easy it is to clean the sensor using a correct size sensor swab with a drop of sensor cleaning fluid on it. eg: VSGO sensor cleaning kit. (follow instructions carefully. And it's worth watching Tony Colthrop's youtube https://www.youtube.com/watch?v=240DGR4u_0M
Personally I don't delete photos until I can view them on my computer.
The Pros you mention are why I'm hoping to buy an a7Rii soon.