Why don't you like Mageplanar speakers?

Devilboy, Magnepan is one of the largest high end speaker manufacturers, with over 100,000 sold. If so many things had to line up for them to work, that wouldn't be the case. As it happens, few of us have setups that are ideal for Maggies, or for any speaker. But they do quite beautifully even without, indeed, like other line source dipoles, they are less sensitive to room acoustics and require less room treatment (the flip side being that they're more sensitive to careful room setup).

If the 20.7's sounded bad, it was the dealer setup. Period. Nobody who has heard them has had anything but raves. Dealer setups are a chronic problem with Maggies, they almost never sound right.

I suggest you listen under better circumstances. They won't work close to a wall, no dipole will. Those who can't pull them out should get boxes -- most boxes aren't at their best against a wall either, but they do better than dipoles -- or a dipole that's specially designed to be used on a wall, like the Magnepan on-walls or the Wisdom in-walls.

...But, I do like Magnepan speakers, but, I like a few (and I do mean a few) other speakers more.

For a basic box speaker to be really inefficient is something of a design flaw. However, if it's not a box speaker, then I think different standards apply. It's also just as easy to say that low wattage amps are a design flaw since they don't match well with really good sounding low efficiency loudspeakers.

Maggies were born in another era when SETs were the not buzz. It was an era of very large ARC tube amps that only made 110-150 wpc but were biamp'd into tympanis with unprecedented results. They are a small company that has changed little, offering its time tested formula at ever more reasonable pricing compared to an often ludicrously priced competition. It works for Magnepan, if it does not work for you, they and you can live with it.

It's also worth noting that there are planar magnetics that do use neodynium ribbons and give you amazingly high efficiencies, like the Wisdoms and Graz's Apogees. However, one look at the price of these and most people will gasp and go back to the Maggies and a more powerful amp.

Magnepan does use neodynium magnets in some models, where nothing else will do the job.