Kettleman
I moved my reply to this thread so as not to make a mess of the other one.
I don’t totally agree with you, based on a Seb 31 sample size of uno (and a number of 21s). So let’s have a big flame war !!! That is what the internet is all about

! The following is my opinion and worth every penny you pay for it.
I think an update around 31 years (28?, 32?) would have happened, Chris or no Chris. I agree Tim and Anne needed to do it to show they could continue the brand without Chris but it seems inevitable anyway. The iconic sebenza wasn’t going away and I don’t think they would just keep producing the 21 perpetually. Updating a model like the Sebenza is a sales driven thing, to stay relevant, and also a chance to make manufacturing more efficient (cheaper).
I would think the ceramic interface is less labor intensive and more consistent than manually carburizing the lock face on the 21. It’s an evolution in manufacturing as much as it is in knife design, including on the 25 and Inkosi. Would Chris have made that change to the Sebenza? Seems logical, but we’ll never know for sure. If he thought it was incompatible with the bushing, I kinda doubt Tim and Anne would have done it (pure speculation). Mechanically, I cannot think of why the ceramic ball would not be compatible with the bushing, but I’ll have to think more about that.
My son’s 31 is less than a year in his pocket, but carried every day. It’s a fraction (minuscule) less smooth than my current carry, a decade old 21. I think it’s only a matter of time until it’s just as smooth. We’ll see. The 31 does seem to take longer to break in due to higher lockbar tension and ceramic ball.
You may now commence the name calling