Evidently, everything is imported from WSJT-X and there is nothing to be configured! when switching from WSJT-X to JTDX:
JTDX + Flex CHECK (CAT, audio - it's all there and working)
JTDX + JTAlert CHECK
JTALERT + ACLog CHECK (even though I'd also installed the latest version, this time clicking the option to allow it to talk to JTDX - an option I'd left unselected till now)
There were not even any minor things to adjust, select, configure or curse at. I do have to get used to a new layout and find all the right buttons, etc. And I'll have to learn the numerous filtering options that JTDX has - this is probably JTDX's main appeal to those who use it.
And to top it all off, 20m seems in good shape.