If I'm not mistaken, they both use the same 640 Micro II thermal core.
I'm guessing your looking at the MK1 50mm or 35mm?
I like that the bolt base mag is 3.5 vs. 3 of the MK1 for hunting coyotes in open terrain.
I don't recall if you stated if this will be mounted on a bolt action or an AR platform but if this was intended for a bolt-action, I would go with the bolt vs. the MK1.
Bolt is 3 or 4 oz heavier if that makes a difference to you.
tough decision, at this point i think you have did your due diligence and your going to enjoy either one. In the end if you're not satisfied with your purchase, you'll have no problem reselling it to one of the thousands & thousands of guys that purchasesd 384 units in the last 2-3 years.