Epsilonman,
As you point out, the IRS V -- surely one of the greatest speakers ever made -- cost $60,000, and that was when it was new. The priciest Maggie goes for 1/3 of that, 1/6 when you factor in inflation. So you're comparing apples and oranges.
I can't agree with you on comparisons with the smaller Infinity models. They had their virtues, and their problems. So did the IRS V, like any speaker, but it's virtues were so overwhelming that it's hard to argue with it.
I think the big Genesis 1.1's, the speakers most comparable to the IRS, are over $100,000. For that, you could get five pairs of 20.1's and 20 pairs of 3.7's! For which reason they are of practical interest to more of us.
Magenpan had the quasi ribbon before Infinity and Jim Winey apparently wanted to use it in his original production model but didn't, for reasons I'm not clear on. In any case, it's being used now. And it's worth noting that nothing, including the IRS V, has ever equaled Tympani midbass. Sure, the Infinites went lower and louder (although the only time my 1-D's ever bottomed was on cannon shots on the Telarc I812), but the servo woofers couldn't keep up with the planar mids and tweeters, and to my ears, the Tympani woofers are the best ever made, combining as they do planar clarity with dynamic slam. If I did want to go lower and deeper, I'd just add a sub -- one contributor here actually has Bruce Pick's rotary woofer mated with his Tympani IV panels! That goes down to 0 Hz.
By the way, I understand that the 1.7 and 3.7 no longer suffer from the "Mylar sound" that bedevils large planars. That at least is what the reviewers say, I haven't heard them. The foil conductor/Mylar sandwich seems to do a better job of damping traveling waves than the wires. It's never bothered me; I can hear it if I listen, but normally I just tune it out. Unfortunately, all speakers have self-noise of one kind or another. This of course is a matter of taste, it's a sonic flaw and if it bothers you, it does.
Also, as I understand it, Mylar is actually a better sounding material than Kapton for planar drivers. The reason Infinity and other manufacturers used/use Kapton in smaller drivers is that they have to dissipate more heat, and Mylar has a lower melting point.
The reason the smaller Maggies aren't push-pull is, again, one of cost. The 20.1 is push-pull. I don't think you can get away with single-ended in a small driver like the EMIM's and EMIT's, the distortion would be too high.