Individual speciments of M1 *can* perform sub-MOA, sometimes even at or maybe slightly under .5 MOA. In both .30-06 and 7.62mm.
Statistically speaking, more of the M1As will attain those levels of performance. The trend for slightly better performance by the M1A has been proven in both rack-grade and in match-tuned guns. Part of it is the rifle. Part of it is the ammo's "inherent accuracy." For super-tuned benchrest bolt guns, the small-group record for .308 is, I'm sure, smaller than for .30-06. But for most of us (at least me!), the difference between .188 c-t-c groups and .24 c-t-c groups at 100 yards is NOT useful.
How good is good enough for you? If 1.25 MOA will fully satisfy you, there's no reason to NOT get the M1 if that's the action type you prefer.