Andy2,
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.
Best regards,
Duke