Ah–I didn’t realize it was Retina display.
I don’t know of any reports of corruption if downsaving/updating frequently, but then again, I’ve only had to use that workflow a few times in the past. I do know that workflow is a pain in the butt. So I will feel your pain. Thankfully, we no longer have that issue.
We have all the versions of InDesign, so we normally just keep it in what the client wants.
Maybe I’m worried about corruption because Quark was notorious for corrupting when downsaving/updating frequently.
We too have a client who is only at CS6 and they don’t want to upgrade either. And others are at CC and refuse to go to CC2014, and some are at CC2014. We still occasionally get in CS5 files, and they want it kept in that.
Why things reflow/line breaks change is beyond me. I do know it happens. It’s not usually something severe, but it does occur. A line here, a line there. Sometimes nothing changes at all, but in other jobs some line breaks change.
It’s just something to keep in the back of your mind.