JBL EON 315 or JBL EON 515/XT?

I've decided I'm going to go with the JBL Eon PA System, I am for sure getting the JBL Eon 518s Subwoofer and I am either going to pair it with the JBL Eon 315's or the 515XTs. The question is whether to spend 400 more to get the 515XT or will the 315's be sufficient with the subwoofer for DJing outdoor house parties