I get that you are happy with your Crystal.
I already consider my Aero which is lighter than a Crystal an issue and my priorities are different from yours. You already know my feelings about Pimax as a company and the fact I consider that kitchen sink design an abomination, so the BSB looks like heaven to me.
I think there is a very good chance that the BSB will be a slam dunk in terms of my preferring it and sticking with it long term until smaller options are available.
We'll have to see if I feel the same way in two months.
Agree that's why I said: "extremely subjective" about what visuals are
good enough and if it's worth it to trade visuals for it's form factor. To me personally the visuals can never be good enough until we reach real life visuals and we are decades away from that(if ever), so in my opinion the BSB is already a HMD from the past because the downgrade on the visuals is pretty significant compared to the Crystal: less resolution, way less brightness, less smooth(75Hz), less FoV, glare, poly material lenses instead of glass, small edge distortion I understood from reviews too.
A human head weights around 5 kilos for an average human, adding one kilo to that or 130 grams doesn't make such a big difference at all. It's a exaggeration to call the Crystal a "kitchen sink" for that reason, I am not build like Arnold Schwarzenegger but the weight of the Crystal is with my headshape an absolute non issue. Even after many hours of driving, my neck/head etc. has zero issues and the wobbling is not an issue too. I think that the vacum/sweat/used material story of the BSB is a bigger issue then the weight of the Crystal. Yes if your headshape doesn't fit the Crystal then it's surely an huge/unsolvable issue, but if it fits okay, I honestly don't see an issue for sim racers.
Of course we all have different priorities and I would even take the BSB over the Aero because of its probably/hopefully: better stereo overlap, better colors, better vertical FoV I assume, better blacks, hopefully less edge distortion, no motion blur, less chromatic aberration, less colour shift. I would trade in the nits/resolution for that probably.
But with your mindset I do believe that the BSB is going to work out for you! Because you have the form factor/size/weight of the HMD as high as possible on your HMD priority list. And of course, the BSB is unbeatable with that.