Hi Peter,
I had been preparing a response. It doesn’t go very far beyond what sezare56 says already though.
As to the first part, the silence that you get when saving … my recollection ( a foggy one ) is this has been attributed to a hardware design issue, rather akin to the relative slower rates of saving / loading of patches. I think it may relate to the process involved with storing to non-volatile memory. ( For example : needing to pull a bus away. )
The second part ( about being able to save alternative system setups ) is ( to me ) a more interesting problem.
Your approach is to my knowledge the only way to work 'round this problem. I am not aware of any SYSEX or NRPN that makes system changes, apart from some very limited changes with NRPNs, like changing the source for CV gate, between keyboard and ribbon, turning overflow on and off, and changing some of the aftertouch parameters.
I first tried to think of other hardware synths that have approaches to handle this need. Elektron has some of this, being able to store some “working states” in projects.
But what i was looking for was hardware synths, that allows you to have separate users, ( USER1, USER2, USER3, … ) with separate system setups, like on a computer, and a way to go between “users”. I couldn’t really think of one. ( Did the Korg OASYS have this, i can’t recall for sure, it might have ? )
So another way this gets approached is for companies to pull system parameters into patches. A prominent one i thought of, is a Behringer firmware upgrade, making the really extensive vintage “atrophy profiles” on the UB-Xa, part of every patch, instead of a system setting. The atrophies can have really extreme affects on the sound, so it makes sense to have them part of a patch. But that doesn’t cover the situations where you want to have two independently variable groups of stored parameters.
As far as ASM doing this with a HS, i thought one place to look at possible future options for this was on the LS. But the implementation there, for this sort of thing, is pretty much the same as on the HS.
The Diosynth, with a different focus on use, does have a few parameters that can be either global or patch settings like scale and tuning.
So like i said i don’t have too much to add. I think you might want to consult with either Ken ( @Flux302 ) or Glen ( @GDarcey ) to see what they may have to add.