Just sent the paperwork out for a Mega last Friday. Have heard only good things about them. I have a feeling that stripped lowers are going to be hard to come by in the near future. I'm going to stockpile a couple of these and some parts kits over the next few months.
I built my 6.8 on a Mega lower and upper. The fit between the two is really nice. My only comment is that the finish seems a bit thicker than on other lowers. My first build was all RRA and the parts kit went in with relative ease even though it was my first build and my tools consisted of vice grips and a drill bit for a punch.
The Mega lower with an RRA parts kit was a bit of a struggle for me even with a proper set of punches. The trigger group pins did not want to go in. I dinged the finish during the process. That being said, I have two more to build and don't regret having them. ;D I like that they are marked Multi too... Something about having a 5.56 marked 6.8 does not sit well with me.