Let me expand a little on my experience with these speakers. I heard the ML Ethos (€8000), the Quad ESL 2805 (€7500) and the Manepan MG12 (€1800) and 1.7 (€3000), all on different occasions, at different dealers, with different electronics.
The MLs sound very dynamic and can go pretty loud and low. Integration of the basswoofers with the panels was not an issue for my ears. What was an issue for me: harsh trebles, more prominent as you crank up the volume. And, unlike what the dealer told me, they need excellent amplification. The bass is taken care of by the inbuilt amp, but impedance drops very deep at higher freqs (<1 Ohm IIRC). So your amp needs to be stable into very low impedances.
The 1.7s sounded really gorgeous. As Hoops says, if your amp feels OK with 4 Ohm loads, they're quite easy to drive... They do appreciate high current amps though, which make them sound even better. Their major pluses are their speed and timbral accuracy. The bass is not so prominent or deep as the MLs' but of good quality.
After the 1.7, the MG12 was plainly disappointing (I heard these two on the same day) -- there's a price difference, and it shows. I really thought something was broken (amp or speakers), but it was just in a lower league.
Nothing had prepared me for what the Quads delivered. Must be the combination of ESL panels and a crossoverless design, they sounded very lifelike. Like I remembered the Maggie 1.7s, but more and better. It took me days to kick the experience! Drawbacks: don't do really loud; bass extension is limited (go for the 29s if that's an issue); and they're huge! They don't easily blend in! As for amplification: unlike other ESLs, they are really easy to drive, with 8 Ohm nominal and 4 Ohm minimal impedance. As they are inherently limited in SPL they can produce, they don't need a high power amp either.
Unfortunately, I just don't have the space to do them justice...
As always, let your ears be the judge. You're lucky if you can hear them all at once!