I have to say that this whole post has me somewhat confused. Surely if you used a SLR with any long lens without image stabilisation you would have to up your shutter speed because of 'mirror slap' and on better quality SLR you can lock up the mirror to mitigate the problem. So surely 'Mirror slap' would have the same effect as 'shutter slap'. So the problem as I see it is that on the A7r you have no mode that equates to 'mirror lock-up' but with the A7 you do as you can have the electronic first shutter.. I hardly feel this is a reason to slam the camera just use a higher shutter speed.