I wouldn't worry about a DPMS barrel being inferior. Most all AR manufacturers don't manufacturer their barrels anyway. They purchase "blanks" from an outside source and do the inhouse boring to their specifications, OR if they're just an assembler, they purchase an already bored/exterior finished M4/heavy/pencil/government type barrel or whatever special fluted barrel they want from a barrel supplier. BCM and FN also do Hammer Forging with their barrels, which adds another dimension of metal treatment to a barrel for quality.
Also, DPMS is being used around Afghanastan. Don't believe me, just search for "DPMS bring backs". The Uganda government is using DPMS as a guard rifle for support troops/supplies. Yes, DPMS is still only a semiauto, but it's being used in/under a war situation.
Not all do everything that an AR company wants but supply the blanks. All barrels makers also do barrel steels according to what the gun manufacturer needs. So Colt might want a steel that has different alloy makeup of metal blends than Del Ton, but the barrels come from the same barrel maker.
McGowen does make a very good barrel, but DPMS also uses barrels from wherever they get them, that give very accurate results too in their "Un-lined" makes.