Hi all, I have a 5K "retina" 27" iMac that I have greatly enjoyed using. I'll be away for work for about a year with my MacBook, and will be leaving the iMac at home. To mitigate the pain of going to the 12" MacBook screen as my main computer, I was considering getting a 27" display for the year, and then bringing it home afterward... as I had been wanting to get a second display for the iMac, anyway. The trouble is, the MacBook can't drive anything higher than 4K. My question is, has anyone used the 5K iMac with a 27" 4K display, and if so, is it very noticeable and the external display isn't 5K? I'd guess that it'd be difficult to tell at a glance, although windows would resize between the two displays which could be a nuisance. Any thoughts?