The woofer question is interesting. My speaker did not have the Alpha woofer, but a much deeper dimensionally and over one pound heavier woofer. For me, this is a personal taste thing. The woofer played the deepest notes when there, but bass above say 50-60 hertz seemed missing too much of the time. It seemed like a gap to my ears.
The Beta woofers are spec’d on paper to not go as low as the Eminence bass guitar woofer I think is being used. However, in cabinet performance is a diffferent thing. I did have a chance to A/B both drivers and found the Beta more musical with plenty of mid bass. I happened to find the deep bass satisfying also. Perhaps not quite as much deep bass foundation at times. Eric is right that the Beta has more mid bass. In fact so much so that I found adding some damping to the rear cab wall really helped tighten up things.
When I upgraded the in series cap to a film Mundorf, used thicker gauge wire (Duelund) and damped the back wall of the bass cavity, then the bass became tighter and even more pleasing.
Eric uses a very good stock woofer and frankly I would spend my money and time on the Mundorf and Mills parts along with great thicker gauge wire and back wall damping. For damping you can use acoustic foam egg crate style or even poly batting. Just cover the back up to the top most brace ( right below the upper array sub cabinet) and be sure to leave the ports free and open.
Eric is also spot on in that I use DSP to boost bass from 20-40 hertz. Now I have plenty of beep bass and nice mid bass.