Agreed, they’ll want to do a truckload of testing with alternative burrs before they sell any. And it may simply be something they have no interest in.
Dave has started with a mini test with 2x SSP burrs. The key issue I suspect is the burr dimensions. I’m equipped with a dozen or so burr sets the Micrometer that Dave recommends and I will initially measure all burr sets and record.
Based on my testing to date with variousvgrinders, the significant (and helpful) difference with the Duo versus the DF83 is that the former uses coil springs versus the latter’s wave spring which gives the Duo a fraction greater depth tolerance. Meaning it will tolerate a marginally thicker burr than the DF83.