PROMYS or SUMAC?

Which one should I go to? PROMYS or SUMaC Program I? I know that PROMYS is cheaper and longer, and much more intense, while SUMaC seems to be more oriented on higher math. Can any previous campers give their experiences on either of these two camps? Also, I already know a lot of abstract algebra, including group theory. Will Program I still be a challenge for me?

Neither. Apply to HCSSiM.