TL,
I don't know if I have enough time with the 6.8 x 43 SPC to be a judge or even offer an opinion that will be valuable. I bought the DPMS as part of a group dept buy. The DPMS rifle is well made. Mine is a flattop with a Wilson Combat iron sight providing a mount rail for a MicroDot 1.5-4.5x20 illuminated scope. I also have the collapsable stock with a tactical sling. The AR-15 / M16 style weapons are not my favorite. Back to the 6.8 SPC. I look at the round as being a .270 Win 'light' (my own definition). Here are some stats that show why I think its better than some and not as good as others:
Caliber Bullet weight Velocity @ 200 yds Energy @ 200 yards
.223 55 gr 2304 648
6.8x43 SPC 115 gr 2285 1333
.270 Win 150 gr 2183 1587
7.63x39 125 1783 882
30-30 Win 150 1605 848
.308 Win 180 2198 1930
Now, considering maximum force applied to target, I prefer the .308, hence my enthusiasm for my FAL (I also like the overall fit and concept of the FAL. I believe I would also enjoy a SOCOM 16, if I were to luck into one).
Considering the availability of AR accessories, the AR-15 type weapons clearly have the market cornered. You can buy most anything you want to add to or modify this series. These are now offered in a variety of calibers. When I bought the 6.8 SPC it was ballyhoo'd as the best compromise chambering for Law Enforcement, having the same approximate velocity as the .223 plus a down range energy of twice as much. In reality ammo was almost non-existent. Last year, I was lucky to get 1st quality ammo to sight in, qualify, and load two spare magazines. Let me digress here: high quality AR-15 / M16 magazines are $10 ea., 1st quality 6.8 SPC magazines are $43 ea! This year ammo is more plentiful, but still somewhat limited. Bullet choices remain limited also. The bright spot is Hornady redesigning the casing for improved functioning (in all 6.8 SPC weapons) and going into production. I note that I have never had a functioning issue with this gun. I haven't shot anything of substance to evaluate the effectiveness of the 6.8 SPC round. It punches paper well. The only effective auto window glass penetrating rounds I have used are the Federal LE TRU bonded rounds in .223 & .308. They are awesome! If they come out with a LE TRU bonded bullet in 6.8 SPC, I believe it would substantially outperform the .223.
So, that all said, I don't carry the 6.8 SPC except on on rare occassion. It spends most of its life under my bed with flash light attachments to use for utility in power outages and for possible personal defense (if I run out of Glock ammo or the perp is at some longer distance). I qualify with it once a year so I can carry it and to be qualified if I have to take up another officer's weapon. I am currently planning on mounting it in my Yamaha Rhino and leaving it there.
I prefer my FAL.