Ribbon midrange pros and cons

 I’m surprised that nobody mentioned Strathearns that address a lot of the problems mentioned. They are great from around 400 Hz on up.  There is no need for a transformer if you put a couple of resistors in line with the amp.

The old Heil AMT1 speakers had ribbon drivers in a semi-horn bidirectional enclosure that were pretty awesome sounding in the ribbons range, which reached down into the midrange.

A slight correction to Raul's comments.  The  Classé DR 3-VHC is not a 25 watts/ch amp, it is spec'd at 45 watts/ch in pure class A.  The smaller DR 2 and DR 3 were rated at 25 watts/ch.  They could all be bridged and basically quadruple their power while remaining in pure class A.  All 3 amps would be able to drive the Scintillas (and they would deliver full power in class A).

Regarding ribbon midranges, the top model Genesis speakers designed by the late Arnie Nudell used B-G ribbons that shared many similarities to the the ribbon used by Bob Carver in the Amazing Platinum Speakers (I think Carver used Kapton, and B-G used Mylar).  Those ribbons are extremely easy to drive (they are basically a 6 ohm resistive load), and excellent sounding; however, there are no longer produced so they are no longer a feasible option for speaker manufacturers to consider.