The idea of a powered bass section in a 3way by itself is very good , but you have to have line level input only and pair it with powered mids/highs as well. And 8" just isn't sufficient for a "sub" woofer. A loudspeaker wiith powered sub has to be active all the way through - a great example of this being the ATC SCM50SL. Either go all passive with a sub or all active, and really, still with a sub.The more I think about this built in sub speaker, the more it seems like a novelty. If this was such a good idea, more mfg's would be doing the same thing.
If you're interested in a passive full range tower, go old school with one of these babies: