No, the it has nothing to do with the Hardware from the standpoint that you are talking about. The EFX theory has no merit since it has nothing to do with polyphony.

For example, the SC880 has 5 FX processors and what happens is a small delay when switching to and from patches with differnt effect settings. An FX delay would occur, but that would hav enothing to do with processing a large amount of notes, it doesn't make any sense what-so-ever.

I'm almost certain that my theory is correct. The whole "Roland wouldn't release this info" even holds water in my scenario.

It's the simple fact that all of the Super JVs have this Ch X + Ch 16 problem. Everytime you send out control messages on Ch X, Ch 16 will output the same control message.

So get this straight - Filtering out Control messages will not correct this problem. Getting rid of all of the Ch 16 messages on Track X will.

The Infamous EPU.