I have a CQC AUG with the NATO stock equipped and I love the shit out of it. The way mine is set up, the optic is the same height over bore as it would be on an AR, so the BDC reticle is still valid.

Here's a guy selling a NATO stock for a good price, well not sure if it's a relist or not, but they aren't hard to find either way: https://bullpupforum.com/index.php?topic=7413.0