Is there too much lost in the 308 round to cut a barrel to 13.5" vs staying with a 9" 300 AAC AR 15 using the new barnes bullets that expand out to 300 yards?

From what I have read a 150ish grain 308 bullet will be about 2400 fps from a 13.5 barrel. Compare that to a 9" AAC using the new barnes bullet at aprox (if memory serves) 2100 fps, is anything gained using the much larger 308 platform other than bullet weight?

Example:
LMT MWS with 13.5" barrel, weight with optics/ammo around 10lbs, oal aprox 34"

AR15 300 AAC 9" barrel, weight with optics/ammo 7-8lbs (guess), oal aprox 28"

What would the energy at 300 yards be with both guns? Pick the best ammo you can use. Does the 308 out perform the 300 by a large enough margin to justify the extra weight/expense? Think pig hunting here. MWS is going to be about twice the cost of a dedicated 300 upper to add to existing lower (food for thought).

Maybe rsilvers can put it into his software and run a test.