My recollection of the advantages of the P-51 were numerous, but its operating range was predominant. With external tanks, it had a staggering range of nearly 1700 miles which, together with its excellent performance in the role, assured the bombers out-n-back escort, something few, if any, other escorts had the capability to do. I believe the P-47's range was ~ 300-400 miles less than that (and I'm not picking on the P-47).

IMHO, there remains to the current day tremendous controversy re: the effectiveness of the "strategic" bombing campaigns of WWII. I have read quite a bit on this, including numerous monographs taken from German senior staff after the war, and it seems that by mid-1944, things were getting quite difficult for the German armaments industry. What wasn't so effective was the targeting of civilian population centers, as done by the Germans, Americans, and British. The Americans, of course, made an artform of it in the great fire-bombings of Japan in the closing months of the war. Nagasaki and Hiroshima get the publicity, but the incendiary raids on Tokyo, Yokohama, and other large Japanese cities were far more horrific (at least in terms of civilian casualties and property damage).