8850 owner reporting here. From my experience much of the 8820's behaviour, as mentioned above, is also true for this module - possible delays in fully switching (especially when switching every channel at once whilst a MIDI is playing), the lack of need to wait for a patch change command unlike SC-VA, and flexiblity in GM1 and GS resets (have not tested GM2, and XG and model-specific reset messages will force a mode change) all apply.
There are a few caveats with this module:
- INST MAP only changes the map for the currently selected channel; to force the entire module (or at least one of the four parts; I need to test this further), one has to select all parts first (a matter of pressing two buttons), causing "SOUND Canvas" to display on the LCD; afterwards, pressing INST MAP will force a number of channels to the selected mode.
- Using INST MAP globally definitely results in parameter resets; for individual instruments, however...I am not entirely certain and will need to test this more (especially with the use of 88Pro/8850 EFX).
- As always, the 8850 has its dubious compatibility with the rest of the SC line. IMO it is serviceable for SC-55 stuff (despite notable differences versus my 55ST); for 88 and 88Pro material, however, a good 88Pro-owning contact of mine discourages the 8850 greatly.
These are all from prior experiences, though, and I'll be verifying these claims in a bit, when I have the time.
CM-64, FB-01, SC-55ST, SC-8850, SD-20