Here are a few walk-around suggestions to minimize the "sound switching" issue.
1) Left hand voice is never an issue for me because I "Freeze" (Freeze Button function) the Left Hand voice. I create Registration Voice banks. One bank of various suitable Right Hand voices that would work well with a Left Hand piano voice. Another registration bank with a suitable organ voice for the Left Hand voice with various voice registrations that use organ type voices. Thirdly, a custom Ensemble voice Registration Bank. Ensemble voices share the same DSP block, so no sound glitches between Ensemble voice combinations.
The first Registration Sound bank had all my initial settings built into memory button 1. For the Registration Freeze settings (Direct Access - Freeze), I have "Style" and "Tempo" checked on, but keep "Voice" and "Multipad" unchecked. I would press registration memory preset and then press the "Freeze" button to lock the Left Hand piano voice or another left hand voice of your choosing. I use my Left Hand voice to control the chords anyway, so I can at least add some rhythmic type chording with Left Hand piano or an organ voice. With Full AI Keyboard fingering I can easily jump my left hand chording over the LH split point and still trigger the style chords with both LH and RH playing interpreting the style chords.
Even if I have the Left Hand piano voice locked in (froze), both the Genos and the Tyros 5 allow Ensemble to switch back and forth from non-Ensemble voice while the style plays. For me, totally amazing to enter Ensemble at anytime or cycle seamlessly back and forth between a Left Hand locked voice and in my case, a full Ensemble Voice Registration Sound bank. A dream for the live performer. On both the Tyros 5 and Genos, Ensemble voices can be saved to a style OTS memory.
If I want to quickly switch to organ type playing and MIDI bass pedal playing, I cycle to the Organ Registration Sound Bank, unfreeze, press Registration Memory button 1, activate Freeze again locking in the left hand organ voice and I again can cycle through all my mixed Registration Sound Banks while a style plays. Another reason I create Custom Registration Voice banks is to create exact voice setting/parameters I like and create (in essence) a huge custom sound library I can feed off to use directly for Style OTS saves. I am so particular (hopefully not an obsession disorder), that I practically never use a default voice setting or the OTS saves each default style has.
2) Purposely group or select voices within OST saves or Song Registration Memories that use the same DSP effect or effects block to minimize the sudden switching to another DSP type. Example: I may keep the same organ type and rotary speaker effect between OTS saves or Registration button memories, yet I wouldn't have to worry about any sudden noise while the voice changes to another Organ flutage (drawbar setting) or between fast and slow Leslie effect (same DSP).
3) You can also set the Style OTS Link Timing from Real Time to Next Bar, in the Menu-Style Setting-OTS Link Timing. I personally use "Real Time" OTS changes, but I just have to be mindful to lift off my Right Hand notes.
4) This little trick works when you want to use just single Right Hand voices (no layers). Just save the four voices you want Left Hand, Right Hand 1,2,3 and save what combinations you want into the Registration Memory slots or Style OTS memories. No chance of sound switching issues because the voices and associated DSPs are already pre-loaded. Of course you can manually switch on or off voice parts at anytime simply from the panel, but memory saves to a registration or OTS button can automatically make the voice selection for you.
5) I link my MIDI bass pedals to the third Right Hand voice or Right 3 button voice. Another reason to use the third Right Hand voice, because it corresponds to the fourth Ensemble voice. The Genos doesn't care if the voice is on or off on the panel...the voice still sounds in the octave the MIDI bass pedal note plays. This works very well, because sometimes you want the third Right Hand voice to play with your right hand, yet also the lower octave notes to play with the MIDI bass. Other times you don't want your right notes to play, yet you want to hear the bass notes. Again, the bass notes will play regardless if the Right Hand 3 button is off or on. Just to conclude that sound switching issues don't come into play in combination using MIDI Bass board pedals, within the chosen Right Hand 3 voices, mostly because of the reasons stated in point 4).
Hope the above helps. Over the years I managed to minimize the issue, but an issue Yamaha can most likely correct within the present platform/OS or the next Genos/PSR model arranger.
Marcus