No complaints with my 14.7 carbine upper. Run perfect from day one.
Been eyeballing one of those 14.7 middy "unpinned" myself as possibly the next one. Definitely cheaper and less hassle in the long run to pin afterward especially if your even considering a one piece free float tube for it which no one mentioned yet. If the original poster is ok with a birdcage and a limited number of rail options by all means get it pinned ahead of time. Then you can immediately slap it to a non SBR lower and hit up a range upon arrival. Otherwise add your choice of rail, other mods etc...... and then play the hurry up and wait game bysending/dropping off somewhere for pinning. Remember that hurry up and wait time frame beats a big fine and some club fed vacation time. YMMV as usual.