Element on/off isn't something you can modulate (offset, etc) - so superknob isn't going to have access to these parameters. As you've seen, element levels can be modulated so there's a way to use levels to do this. You can even tie an arpeggio to an assignable knob using control ARPs and then, in turn, have that assignable knob "automagically" switch the volume levels of certain elements with one ARP vs another ARP.

Or, even easier, just tie Superknob "directly" through to each element's level and just use the Scene button's control of Superknob to switch between one set of elements vs. another. This will consume polyphony for every element even if the level is offset to 0.

Using A.SW1/2 is perhaps a better way because this method won't eat up polyphony - only one set of elements will be active at a given time depending on your A.SW state. Control ARPs can modulate "anything" with a CC value. Unfortunately, despite the thousands of preset ARPs, I cannot seem to find control ARPs that cover all of the bases. I didn't see any that modulate A.SW. You can "cheat" and set any of the A.SW CC settings to match something that is modulated. Take a look at the data list and look at the "CT/HB" main category part of the "Arpeggio Type List". The last column has a comment about which CC (or CCs) is(are) modulated by this Arpeggio. If you go to the menu to assign CC values - you can change the A.SW CC value to match one of the modulated ones.

NOTE: The data list, at least Montage version J0, has an error in the comments about modulated CC#s. The As1 and As2 ARPs (for assignable knobs) show CCs of #16 and #17 respectively. These are not labeled correctly. They are actually CC#17 and CC#18. I checked the rest of the CC values (spot checked, not 100%) and those were labeled correctly without requiring a +1. So beware of typos.

As a proof of concept, I did this:

1) Pressed [PERFORMANCE] (HOME)
2) Touchscreen (TS): touched the Performance name at the top
3) TS: Touched "Edit" from the popup menu on the left
4) TS: Selected menu "Control" -> "Control Number"
5) TS: Touched parameter "Assign Sw 1" and changed the value to match "Assign Knob 1". For me, this was to set "Assign SW 1" CC# to "17"
6) Pressed [PERFORMANCE] (HOME) again and then TS: touched Part 1, then touched "Edit" from the left-hand side popup to edit this Part
7) TS: Bottom row, selected "Common" blue square.
8) TS: Selected menu "Arpeggio" -> "Indvidual"
9) TS: Touched Arpeggio 1 and changed the ARP, using the ARP category search, to "AS1TriF1"
10) Turned on ARP Master so when I press down on keys I could then see Assignable Knob #1 going back and forth and also A.SW1 turning on/off

Now this isn't something I'd want to leave alone. It would be better to make your own control ARP that just sets an assignable switch to "on" and another that sets it to "off". And by this I mean do not change A.SW to match any other CC value - leave it as default. I'm sure this is possible although I do not have the "1,2,3" right now.

As another note - unfortunately when you match say A.SW1 to the same CC# as Assignable Knob 1 - moving superknob even this movement eventually does indeed turn the assignable knob #1 will not cause the assignable switch to modulate. When turning superknob it seems communication through MIDI is bypassed and a more internal route is chosen. If you manually move Assignable Knob 1 - this will modulate the assignable switch - but that doesn't help scene automation. So you cannot take the easy way out which would be to tie CC#s together and then use superknob.

Of course yet another option would be to split these elements away from a single Part and instead place these into two Parts. Then each Part can have its own arpeggios that are switched by the scene. Say the first Part has "Mute 4/4" as ARP #1 and the second Part has Something-not-mute as ARP #1. And vice-versa for ARP #2. It's not a very efficient solution in terms of resources - but is easy to setup.

I've also tried playing with using XA control to assign AS1/AS2, but not sure how to enable/disable assign switches on a Scene change.

You're REALLY close. This is the way to do it.

Have a scrounge around for existing arps and preset parts and performances that do this to see how it's done.

On saving them, you'll have to set the Scene save options to save the assign switch states, and then shift+scene# to save in that state.

This way, when you switch Scene, arps and assign switch statuses should change, and you can hope from Elements1-4 to Elements5-8.

Quite a few of the EDM type sounds do versions of this. Sorry, am not near MODX to tell you of an exact example. Most of them have AS1 or AF1 in their name, I think.

"MA_Ambient 3 AF1" will turn on A.SW1 but it also modulates cutoff.

The other similar ARPs that handle AF1 (A.SW1) for you do other things too - not just a clean A.SW1.

If modulating cutoff or resonance or pitch bend or (etc) doesn't make a difference - you can use the above or any of the other "AF1" "AF2" "AF1&2" control ARPs.

"MA_4Z_HybVel7 AF1&2" turns on A.SW1 and A.SW2 and doesn't mess with cutoff or resonance - but it does modulate pitch bend. If you have pitch bend turned off - for the part - then this one may work as-is.

Turn ARP Hold = On. Switch real-time. For the "Mute" ARP (to turn off the A.SW) you can use Mute 1/4 or some smaller "measure" when using real-time. Or you can switch by measure if this always needs to change on the downbeat of 1. Change the mode to "Direct" for control ARPs so your fingers play the notes as control ARPs are not going to (and telling a pure control ARP to "sort" or "thru" will result in silence). A pure control ARP only knows how to turn knobs - not how to play notes. Without "direct" - you tell the ARP to take over knobs AND notes.

You may still want to create your own control ARP that doesn't do all of these other extraneous things.

Here's another way that I would like to be able to do such a thing in the future, but with much more versatility in controlling ALL the elements of every PART 1-8 via Scenes:

(I added this idea to YamahaIdeascale!)
Add Element ON/OFF Switch Control to 'Scenes'

https://yamahasynth.ideascale.com/a/dtd/Add-Element-ON-OFF-Switch-Control-to-Scenes/259029-45978

If you like this idea, please up vote it on Ideascale...