Yeah but, 4150 and 4150CMV are not identical. The big difference; Mil spec 4150CMV has .25% vanadium, marginally less carbon than than 4150 (C=.41-.49...only marginally more than 4140 C=.38-.41) and other minuscule tweaks.
Okay, so all you have done to my comment is change it to say that it might be more apt to say that it's like someone who is only going to drive 30,000 miles in their lifetime comparing 75,000 mile tires with 90,000
The conclusion, however, remains the same. Overkill is overkill. For most users, the theoretical difference in barrel life will be of interest only to the shooter's heirs.