Just a couple things about Dub.
Sram didn't do this as a favor.
Last year I built a new bike with Force axs. Not a lot of the prior components can be reused. I had expected to transfer my red 22 crankset to the new bike...Nope!
To run axs 12 obviously you need the new cassette. Well that cassette needs the tooth profile for the new chain, which runs larger rollers in it. Which means the front rings will need the new tooth profile to mesh with that chain, thats only available on the new axs rings, which only fit on axs crankset, which only use Dub...
I love my Sram components. But after this experience I feel a bit used by Sram. This whole proprietary scheme has a kind of scammy, bait and switch feel to it. The escalating cost of the build due to the proprietary components left me feeling like I needed a shower after finishing the build , rather than after the first ride.
When I first switched over to Sram in '13, I bought my first exogram 10 speed setup. 0 regrets. Loved it. I've been a Sram guy ever since. But I think this build cured me.
Bb30 sucks, its a crap design. But pf 30 takes that crap design to an entire nother level. And dub just resizes a crap design into a proprietary crap design.