I think that modern electronics can help to compensate for smaller size. I have a huge really nice subwoofer that I bought in the late-1980s (I think it was nicknamed "The Sledgehammer") and built into a rock-solid but heavy-as-lead cabinet. After not using it for several years I took it out of the cabinet and stored it for the time being.
It is 15" diameter with all the traditional stuff like dual voice coils (something like 2"-3") and a massive magnet (multiple pounds as I recall), non-powered for use with a traditional stereo set.
Today I have a couple of self-powered woofers that work very well but are probably no more than 8", an Altec Lansing and a Klipsch I think, that are more "theater" oriented than old-fashioned music-listening speakers. If your crossover operates at input level rather than output level, I understand that the electronics are easy and cheap with minimal distortion, and a self-powered woofer can then "do its thing" however it wants behind its low-pass filter.