Looking closer at the DD5 there are a lot of things that I like, but something that scares me. The lack of a barrel nut/4 bolt rail mounting setup could be trouble if you wanted to do a barrel swap. as I understand it, there is no way to change barrels right now unless you buy from Daniel Defense... am I wrong? I've also been looking at the Seekins SP10. I'm not in love with the rail, but it looks like that could be swapped out for just about anything else. I've got more homework to do.

I've pretty much ruled out JP, LWCI, and LMT because of weight. I'm certain they all make excellent rifles, but I'd like to keep the weight of this rifle at +/- 8.5 lbs with a 16" barrel.
I could always build off of a Mega set, but of the ARs I own, I've built all but 1 so I kinda feel like I've already done that...