I am also an Acapella owner (Campagnile Highs), have a friend who owns Violon Highs and the new La Campanella and would like to address address several issues: i) maintenance of the plasma tweeter, ii) coherence of the drivers and iii) bass. In over four years, the tweeters have proved almost bullet proof. They have an automatic mode that turns them on only when a signal is running through them, thus significantly decreasing wear on the tubes and quartz rod that generates the plasma. In full time, 24 hour a day use, one might expect to retube and replace the rods after about five years. In the automatic mode, who knows? The tubes are user replaceable and dealers should be able to replace the quartz rods which are not hideously expensive.
Coherence. This is an area where Acapella has been very successful. The mating between the horn and plasma tweeter is extremely good to excellent. The mating between the horn and the woofer can be very good but is dependent on the amp used and on placement in the room and cabling. This improves greatly during break-in but it does take the woofers a long time to break-in/loosen up. As this happens, efficiency improves, the woofers play lower in frequency and are more dynamic. None of these (with the exception of the La Campanella) is really a near field speaker. They benefit from a larger room. In the wrong room with the wrong associated equipment, some sounds may localize on the midrange horn. Having said this, even the Campaniles benefit from a really excellent subwoofer but only with respect to the bottom octave. Acapella seems to have made a conscious choice to design for coherence over having the bottom octave. Normally this is not a problem, but with an really excellent sub there are gains in depth, image density and low end power where present on the software. This is a really easy speaker with which to listen to music.
As you might guess, the Acapella cables are a really synergistic match for the speakers. Acapella uses the Einstein electronics to voice the speakers at the factory and the combination is magical.