I got a matched set just cause and while the only thing I can see is any different is that I don't have to add a wedge to keep things tight and it looks cool Later,
The fit on the Quentin Defense billet set that I bought sucks. It's the worst of any of my uppers and lowers. I tried to contact them but they didn't respond. I'd spend my money on upgrades to the barrel and/or trigger. I've got several forged ones that will shoot single ragged holes at 100 yards.