Everything else being equal, the 4150 barrel should last longer in theory... Kinda like 60,000 mile tires vs. 80,000 mile tires... one will outlast the other, but they are both wear items. You decide if the premium for longer wear is worth it.
That analogy may be overstating things somewhat. The range of alloying elements in 4140 and 4150 is identical except for the amount of carbon (40/100 percent vs. 50/100 percent, on average) and except at the limits of mechanical performance makes little difference, particularly in the case of a semi-automatic-only rifle.
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 80,000 mile tires. For most users, the theoretical difference in barrel life will be of interest only to the shooter's heirs.