Why don't you like Mageplanar speakers?

Lack of dynamic range, too much surface area.

Charles1dad, what Maggies have you heard? Your description sounds very different in some respects than my own impression, e.g., realism? As Jonathan Valin just said of the 20.7's, "The listeners for whom the 20.7's are very nearly ideal--for whom Magneplanars have always been ideal--are those seeking the absolute sound. These Maggies' magical ability to transport listeners to a different space and time and to there realistically recretate (with lifelike scope and size) the sound of acoustic instruments and the venue they were recorded in is extraordinary." I think most people would second that, while agreeing with some of your other objections, e.g., limited dynamics. Kinda makes me wonder what you've heard, and where.

"As well as they did many things, realistic bass with "slam" was not one of them."

Photon, ever here the Tympanis? Near-dynamic slam and extension, combined with planar naturalism. Overall, it was the best bass I've ever heard. Of course, they aren't made any more.

Ditto for rock and roll, my 1-D's would rock out. A friend measures 120 dB+ SPL's on his IV's, which is more than all but the largest dynamics can manage.

For those with the single panel Maggies, a pair of subs will address these issues. Subs sound smeared by comparison to planar bass, but for many the tradeoff is worth it, and it's the same bass you'd be getting with a dynamic setup.

Size I don't know how to fix. :-)

Magnetic planar speakers have serious shortcomings, as do most technolgies employed for audio. I could list three for four of them, and in fact in an upcoming article I intend to do so. But don't tell that to a Maggie fan! :)

Josh,
I`ve heard maggies many times over a 20 year period, most recently the 1.7 and 3.7(have`nt heard the 20.7 model). As I`ve said I like them but don`t love them, there`re other speakers I`d prefer that`s all.If they suit your needs then that`s all that matters.
I realize there`re components and speakers I simply adore that you or others may not care for much at all.

We all recognize this is pure subjectivity, nothing more or less.What J. Valin hears has no bearing on my own experiences i.e. different ears and preferences.
Best Regards,