Great response, Kenneth. I'll definitely check that lenses out. Thanks!
I've read some early reviews on youtube and nobody mentions any overheating problem at all -maybe the problem with the a7rii has to do with the huge amount of megapixels compared to the a7sii. However, rolling shutter is disappointingly quite similar to the previous version, as you can see here: https://www.youtube.com/watch?v=bPyKTtIe2CY