No Sound, +1 Sound or +2 Sound is really a personal preference and will often be dictated by affordability and with whether your hoping to have a functioning staff straight away or gradually. Have read here at the Forum (can't remember the Thread Topic) that the configuration has often started with a Warrior Tier with Vented Coupler and then adding a Champion Tier down the line (or vice versa). When it's No sound it simply raises the debate and opinions of the importance of sound. Me personally, sound is a must. Each to their own.
With +1 Sound, you'd still get full functionality and effects of the audio but depending how attuned you are to audio waves, during say a spin or twirl of said staff, it may yield an unbalanced result. Think of when your watching TV through MONO sound versus STEREO sound. At low levels (volume) it is more noticeable than compared to higher volume. This translates to the speaker output and your volume setting.
With +2 Sound, well with above analogy, it's comparable to Pro Logic 5.1
As a staff, specifically a Bastion Staff, both ends will be Bastion. Aesthetically will be great, doesn't make a difference. Running it as a +1 Sound setup I can't see how it wouldn't work. As a single the vented Pommel at base and accented on the sides would provide good resonance. Granted these aren't there when you fit the coupler but I still wouldn't think there'd be any restriction or muffling even if sound is coming from one side only.
37+26 might have been done too. But I think it was solely for display only and (if it's the same one I'm thinking of-looked mammoth and mean). Most of the Members here where they've mentioned their height as 6 Feet+ even with single hilts prefer a 32. For a combined reach of the joined hilts+coupler+26+37 it would be massive. If you were all torso and all arms with average height it might work. Even if you were all torso and short arms too. I would just question great loss of manoeuvrability and wield over status size.
It is a generalisation, but I believe the 'trend' or preference would be agility & manoeuvrability with pace over strength of impact.
What conclusions have you drawn?