My gut tells me it doesn't make any sense to mix coins received as mining reward. These are virgin coins and so there is no history to track, therefore no reason to mix. Am I correct? If I am incorrect, why?
Coin that is issued to budget proposals are pretty easily identified, so for privacy those should be mixed.
It's not the people upstream from your coin that you should worry about. It's the downstream people with poor OPSEC you need to worry about. They drop the breadcrumbs to your door.