I would not get mad at your dealer for making stuff up. But,,,
That sounds like total hogwash. If you order a pair of 20.7 they enter it into the ’current daily cycle’ which is just getting it into the production lineup schedule. Sadly, right now, the vast demand for The new Magnepan LRS is causing production backups of all speakers. So to ’get in line’ no matter what speaker you want. at this point, due to the demand for the LRS is at least 7 to 9 weeks. Magnepan is pretty much a order it then schedule it and when your number comes up they build it. No special treatment for anyone to ’cut in line’. Magnepan has piles of parts already built, and just waiting to be assembled... So you are just waiting for them to get to your order.
Anyway, another reason no one would carry the 20.7 as a demo unit is the high cost. Few dealers have the money to carry something they do not sell many of. MY local area Magnepan dealer HAD a pair of demo 20.7 about five years ago. I went and listened to them twice for several hours each time with my own music. (At that time I owned 3.6 Magnepan. I decided not to buy the 20.7 at that time) A while later when all the possible customers he knew of in the area had given thumbs up or down, he sold the demo pair. Why carry something only one person in six months wants to hear? and then only one in four buy...
Anyway, come along last year I was all set to buy new 3.7i and decided Hell! jump the shark and go big. So I ordered a pair of 20.7s (since I already had listened to them)
At THAT time took them about three and a half weeks from order to ship. Then due to a flaw in the first pair, Magnepan sent a new pair in one week to replace the first pair. (serial number was 3 higher. so you can speculate how many they make from that at least a bit)
The limiting factor at Magnepan is number of employees. To be fair to all Magnepan buyers, they schedule for any model in a linear fashion. Want a LRS, a 3.7i a 20.7 ? same wait. (though I could see a cancellation might get you in faster for something like the 20.7 (plus my replacement was rushed, little waiting) Also my dealers guys set up both pair of speakers, no problem.
Have you thought of GOING TO MAGNEPAN factory? Call them and ask them if THEY have a pair of 20.7 you could go there and listen to?