I think another big problem is the difference between the 464 and the 664/6128.
Where the 664/6128 uses volumes 0-15, the 464 just uses volumes 0-7!!!
The 464 simply repeats them!
0,1,2,3,4,5,6,7,0,1,2,3,4,5,6,7 -> 16 values.
The 664/6128 has 16 real values:
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 -> 16 real values...
This makes it very hard for sound developers to create things working on all machines the same way!!!