Personally, I think the first question to decide is whether you are building an active or "passive" system. If the former, and assuming that active means DSP capability at least on the woofer, the Qts is not irrelevant but it isn't really what you look at, what you look at is output vs frequency and consider how you compensate. If the latter, then I would say follow the advice (at least in general) in Martin King's excellent primers or follow a published project until you know how to change it.