I've had 3 atn optics so far, two of which I still own. I started out with an XSight 2 and it benefited greatly from the cover with a hole in it to make the picture more clear. I currently own an HD thor and a 4k pro 3-14. I don't have much time behind the Thor yet and am still messing with it to get it right. I do love it though. I have had the 4k out on a few hunts and so far I love it. I haven't tried the cover with a hole in it yet but I have a feeling it won't be necessary, I do plan to try it though. Mine isn't as clear as I'd like it to be, but it is more than clear enough to do the job it was purchased to do. I can't speak to the NV aspect of it, as I haven't had time to do any night hunting yet, and would most likely use my Thor anyways because ND doesn't allow the use of IR illuminators which are necessary to use this scope 99% of the time at night.
They did recently come out with a Firmware Update and it did make the image a bit clearer along with fixing some other annoying bugs. I am a member of an ATN group on Facebook and I can honestly say that of the issues people are having with their scopes, probably 85% of them could be avoided if people would simply read the manual, and use the search function in the group to read up on how these scopes work.
I will say this, don't use the Ballistic Calculator until you've had a chance to thoroughly test it out and verify it's accuracy. I was out at the beginning of the week and didn't realize the BC had somehow been turned on. I haven't had a chance to test it out and for some reason it was throwing my shots about 8 inches high (checked it later in the day). It ended up costing me 2 coyotes that day. One of these days I'll get out and test it out to 500 yards and see how it performs, but for now, it will stay off. I have heard from others that is actually pretty decent, so I'm guessing it's probably user error that has it all wacked out.
Anyways, if you have questions on the scope, ask and I'll try to answer them for ya to the best of my ability.