Cuprajake Doesn’t seem to be a huge second hand market for the duo
Personally speaking, I don’t think the “Duo” concept (burr swapping between filter and espresso) never really caught up for a daily basis usage. Dfk says himself at the end of the first paragraph in the opening post.
I really think the single dose grinder space is really saturated, even more so in the micro cosmos of this forum.
As for the grinder itself… I can’t fault mine. I put beans in, I turn it on, I wait 30 seconds and I turn it off. No bellows, no RDT, no knocking, no hot starting, nothing. Just plain old boring and designed to do exactly what it is meant to do - and very well.
Good luck with the sale DFK. An almost £200 reduction from the original price, for a grinder that is not even 3 months old, is the bargain of the century, and with both burrs!