I've had 4.5's and RS11b. The RSllb is far superior. The higher and lower mids are wired to limit high frequency, so vertical dispersion is not beaming. The middle EMIM goes up to a higher frequency. The 4.5 loses focus if you are not at exact center of the midrange. The RSllb does not have that problem.
If you really want the RSllb to be a world class speaker, disconnect the two 10" woofers. Get a 36"h x 24"w 3/4" wood panel and mount an open baffle 15" Eminence Alpha 15 woofer. You'll need an electronic crossover. This will provide a seemless open and box free natural sound to match the EMIMs and Emits. Of course you'll need to biamp. One more thing, the open baffle woofers will only go down to about 50 hz, so add a good sub for the bottom octave. I use a HSU 15"
If you really want the RSllb to be a world class speaker, disconnect the two 10" woofers. Get a 36"h x 24"w 3/4" wood panel and mount an open baffle 15" Eminence Alpha 15 woofer. You'll need an electronic crossover. This will provide a seemless open and box free natural sound to match the EMIMs and Emits. Of course you'll need to biamp. One more thing, the open baffle woofers will only go down to about 50 hz, so add a good sub for the bottom octave. I use a HSU 15"