In this comparison based on the fact you mentioned high BC monolithics, 6 CM is the answer for speed alone. The 25 is a bit anemic in the CM, and would be better suited in a 284 or PRC case for that type of setup. My 25 CM would only push 133's around 2,700fps damn near at pressure in a 19" bbl, my current 6 CM 20" should push a 108 over 2,900 once I finish forming brass and juice the charge up.