I know a lot of testing in regard to penetration has been done comparing faster, lighter arrows to heavy, slower ones. The results offer no definitive conclusion as to which is better. IMO, the lighter arrow at 190 fps, 25 faster than your 700 grain would produce better results. I have no statistics to back this up but just feel the lighter, faster arrow, with a really sharp broadhead, will get the job done quite nicely. An added positive would be the flatter trajectory with the light setup as you will probably be taking longer shots on the elk than you would on deer. Not as much drop to figure in before taking the shot. And, I agree with JR about being able to put together some heavier sticks for the Centaur if you want. Regardless of your choice, either one will suffice. Good luck.