I have another theory, based on availability on a very well known European online seller… I would say Yamaha is saving the scarce ICs for the Montage series. Availability on that website is shown as 'temporarily unavailable' for MODX6 and 8, 11-15 weeks for the MODX7, 8-11 weeks for Montage 6, 4-6 weeks for Montage 7 and in-stock for Montage 8
So I guess there is some production issues but not replacements right now.
Time will tell!
Jose