MANTRA is a piece composed for two ring modulated pianos by Karlheinz Stockhausen in 1970.
In 1970, Karlheinz Stockhausen composed MANTRA for two ring modulated pianos and shortwave radio. The ring modulators were custom built for the piece and are not readily available. Essentially, these ring modulators had a 2nd Order L.P.F placed immediately after the ring modulator to cut everything above 6kHz. This guy has created a digital solution and provides diagrams: http://www.staff.city.ac.uk/newton.armstrong.1/mantra/
I understand little of what the link above says but I have heard MANTRA performed live (which is not common) as well as seen lectures where Stockhausen discusses the work. All I can say is it is an impressive piece of music, though, perhaps not to everyone’s initial taste. https://www.youtube.com/watch?v=j5tjuKSx7BI&t=1200s
The sounds heard in MANTRA can be heard from an H9. I know because I have heard them, admittedly, within a different context, but heard them none the less. The technical setup for MANTRA is not limited to ring modulators and is a fairly large undertaking. Could the upcoming H9000 effectively handle the entire setup for the piece? Could other current Eventide products effectively handle the entire setup for the piece?
I am using Stockhausen and his significance to all music created during the second half of the 20th century as an example of a problem, which is this: composed music that uses live electronics is being written with whatever the composer has on hand. This is a pragmatic approach but unless performers have that particular piece of gear, repeat performances will be few and far between. However, the real problem is 10 composers are writing 10 pieces using 10 different FX processors that they have on hand and none of them are the same. The result is music that can only be performed based on the availability of early Digitech rack units, Line 6 pedalboards, and a Boss pedal that only does one thing but is the only pedal that does it!
Eventide products may be able to solve these problems now and that would be great! If not, here is an extremely simple yet successful example. Composers know what an E-Bow is so they use it when writing for guitar. As a result, the vast majority of guitarists own E-Bows. Sometimes standardization aids in creativity and people prefer help over hinderance.
Just thought I’d share that observation. 
