I don't know about Anderson's uppers but I got one of their lowers from a LGS last year on sale and it was not worth the money. The magwell is machined too far forward and will not work with magpul magazines and even USGI aluminum mags need a real good slap to get them to seat. Since the magwell is too far forward it creates a lip where the upper overlaps and causes the mags to hang-up or not seat at all in the case of PMAGS.
Otherwise the lower is pretty nice with a good finish and nice tooling. I'll probably insert a 9mm block and build a 9mm carbine out of it since I've been wanting to do that anyway. But I would not recommend Anderson simply based on my sample of one. they may work fine with Anderson uppers but they do not work with my BCM or a friends Daniel Defense uppers.