Maggies are not electrostatics. They are planar-magnetic.
Kal is right - Maggies aren't electrostats and a good electrostat will outperform the Maggies in some areas (including retrieval of low-level detail). But chances are neither will image as precisely as a good conventional speaker.
I'm a dealer for a pretty serious line of full-range electrostats, and I'm also a fan of Avalon speakers. If I were adding a high-end "conventional" speaker company to my lineup, Avalon would be at the top of my list.
I think the Eidolon was in the twenty grand ballpark when it was discontinued, so my comments will be comparing it to fullrange electrostats priced between fifteen and twenty grand a pair.
The Avalon would probably have more precise imaging, play somewhat louder, and have more impact in the bass region. The electrostat would have richer ambience and maybe a little better sense of depth, better low-level detail, and more natural timbre and texture of voices and instruments (though this is something the Avalons also do very well with). In the bass the electrostat would go just as low with superb pitch definition, but wouldn't have the impact that the Avalons do (that's something dipoles inherently don't do very well at). Depending on the particular model, the electrostat might well have a wider sweet spot. The electrostat will radiate as a line-source-approximator instead of a point-source-approximator, so the SPL will be more uniform throughout the listening room (which is beneficial for off-axis soundstaging). Also, not that the Avalons are any slouches in this area either, but a good full-range electrostat excels at long-term fatigue-free listening. Several factors go into this, and I can go into more detail if you'd like.
The Avalons would of course have a higher WAF and probably a lower hidden amplifier cost, as electrostats tend to have expensive taste in large amplifiers.
Feel free to shoot me an e-mail if you'd like information on the specific models I sell. If you have more general questions this forum might be a good place, in case others are also interested.
electrostatic speakers tend to play certain kinds of music well, but generaly, if your preference is rock or blues, stick with dynamic speakers. I've listened to several Martin Logan models over the years and none of them were able to play Metallica like a good similarly priced dynamic speaker can. Also, on some designs, when you listen to music with fast bass and explosive dynamics, with a smaller power amplifiers, the bass driver can lag behind the panels a bit, creating a weird effect. This problem's been battled with by manufacturers of electrostatic speakers, but I haven't seen it being completely resolved yet.
For light jazz or classical music though, most electrostatics will do.
Just what I observed during some listening to electrostatic speakers.
But they do sound good when you feed them the material they like to play.
dynamic speakers are still my preference.
Can't speak for the top of the line 'stats such as Soundlabs but the few lesser expensive 'stats I've heard were fast and detailed but lacked timbre. They had the bow and strings of a violin but not the wood. Same for piano. Anybody, feel free to contradict that.
I haven't been fond of Maggies until I heard the 3.5's (maybe 3.6). Those were excellent at moderate levels. Then again, they had proper amplification and were set up in a good room. I think some must have been broken.
For either type of wide-range planar, forget the budget models. It's not a technology that can be done cheaply AND well. They can be extraordinary and I do own planar magnetic hybrids. IMO, dipoles have more ambience with live recordings. Good speakers don't sound impressive, they sound natural.
Dynamic drivers have a inherent "weight" to the sound that can be comfortable but probably not as accurate. That said, most recording studios use dynamic near-field monitors and tailoring to those would be automatic.
Maggies take a "sh**load" of power to open them up, and get them sounding right. During my audition of the 1.6's, when they were first introduced, the schlock dealer had them hooked up to a 50 wpc amp!!! I was able to hear their potential, and bought them anyway. When connected to a 250 wpc Specton Digital 1 [500 wpc for the 4 ohm Maggies] they really sang, and I was quite happy with the increased fidelity resulting from more than enough power. Something for everyone to keep in mind when auditioning any Maggie.
But no, Maggies are not electostats, as previously mentioned!
NGjockey and Aktchi,
My comments assumed large fullrange SoundLabs or possibly Quad 989 (or whatever its successor is). These big megastats have the diaphragm area to do deep bass.
I have four customers who claim to have measured their full-sized SoundLabs (M-1 or A-1) as -3 dB somewhere in the lower 20's. I was present for one such measurement, in which we got -6dB with the 20 Hz 1/3 octave band on a Stereophile test disc using a Radio Shack sound pressure level meter. The Rat Shack meter is down 4 or 5 dB at 20 Hz, so factoring that in we had a -3 dB point in the 20 Hz ballpark.
NGjockey, I understand what you're saying about the strings and bow but not the wood, and yes that applies to smaller stats but not to the big ones. I have a customer who plays voilin in a symphony orchestra in New England, and before the audition he told me that the only speakers he'd ever heard do justice to his instrument was his personal pair of highly tweaked Quad 57's. During the audition (he brought 90 CD's and it took 2 days!) he told me that not only did the big SoundLabs get the violin right, they also got the cello and string bass right, which he said he'd never heard any speakers do before.
Now I'm not saying big electrostats are the answer for everyone who can afford and accomodate them, but the big ones can do some things that the little ones cannot. And since the original poster was asking for comparisons with Eidolons, price-wise that left the door open for the big dogs of the electrostatic world.
In all fairness note that the planar magnetic Maggie 20.1 and hybrid electrostatic InnerSound Kaya have similar bass extension, and the big Maggie is less expensive than the big SoundLabs.
On the subject of Maggies, they really do need major power to get the most out of them, but even then I personally don't care for them much. I just can't hear the detail and crispness from them I get from other speakers I like much better (for example a well powered PMC OB1, active ATCs, or active Linn).