If you built a 400 hp 8.5:1 cr for every point you go up in cr you'll gain about 3-4% or in this case about 12/16 hp, 9.5:1 = 412/416 hp, 10.5:1 = 424/432 hp etc... Given the fact most street engines are gonna be between 8.5-10.5:1 cr were talking 0-8% hp difference.
It matters but not the end of the world. But unlike other mods it's loss/gain is across the entire rpm range.