with several 15 in woofers per side, i would hope that subs would not be needed for most applications
it is interesting there are all the center driver choices provided to the buyer, but i wish they would pick the one that is best sonically, and say that is THE speaker to buy - i feel they evade some responsibility providing all those choices if the speaker does not fully please, whatever the customer chooses
that said my concern with so many of these large bass driver open baffle models is the integration of the woofers with the tweeter/mid - it seems that neither are quite ideal to reproduce the absolutely essential midrange frequencies (that was my own finding when i had the spatials...)