Just worked with Kelly on a speaker change/upgrade for my system. I did not want the ribbon tweeters of the 20T and so I switched from Model 9s to LR5s and added two SW12 subs. I used the Model 9s for many years and they are very good as I believe they were originally intended as a price-point upgrade to the highly regarded 10Ts. The Model 9s offer some advantages over the LR5s in the areas of bass extension, impact, and quantity. They play well with all types of music and, like all the Aerial speakers I have heard, they never run out of steam when driven with good-quality amplification of sufficient power - Aerials like power but the Model 9s are more amplifier-friendly than most at 90dB sensitivity.
On the other side of the coin, I like the closed box (acoustic suspension) design of the LR5s even more. The LR5s use two 9-inch woofers in a closed 105-pound box that feels like a solid concrete block. I added Sound Anchor's new Signature Stands (custom made for me) and edenSound's Bearpaws for a total speaker/stand weight of about 180 pounds each! Their sensitivity is much lower at 86dB so it takes a stout amplifier to hear them sing but IMO the bass is better defined and has a more natural-sounding roll-off than comparable
bass-reflex designs (including the Model 9s). The trade-offs are that they do not go quite as low (40 Hz) and they require more power to drive. This is where the two SW12s round-off what to my ears is as close to a perfect speaker set-up as I have heard. Kelly suggested I run the LR5s full out (no high pass) and roll in the subs and that has worked out exceptionally well. Having the two high-quality powered subs has allowed me to custom-tailor the bass for loudness, impact, and room interactions. The only thing I would change is to add one or two more SW12s.