12'' or 15'' 2.5 way

I'm fixing to order the jordan/ribbon kit CSS J92R2KIT (just need one more paycheck...). I am going to make active stereo subs to go under them. Since I can get Av12's or AV15's so cheap right now, I am going to put two under each side. Yeah thats overkill, but I want to be able to possibly use them for a ht sub later down the road. My question is this. Would it be better to use the 15's or the 12's? Do you think having 15's under the jordan would look too big? would the radiation pattern be too different going from the jordan to a pair of 15's as compared to the 12's?