Why would you have to export to see an unwrap? lol. If it is made in RC, it can be easily shown directly in RC. 
It’s a waste of time to export everytime.
(btw your idea about having a simple checker texture as a display possibility seems to be a good idea as well. +1).
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For the comparison, you can see in green and red the parameters I use to determine what is best. Is there any parameters else to check out texture quality that I’m not aware of?Â