Mike,
I'm now trying to get back my settings. Before trashing the old system I exported my PM 4.6.1 settings. I'm now importing those back into PM 4.6.5, and it is saying: one or more items chosen for import exist locally and cannot be merged; would you like to replace the local items with the items being imported?
What does this really mean, and how would you recommend answering, so that I get back my setup as near as possible?
Many settings are only a single value and cannot be merged. Things like color class labels, colors, thumbnail labels, renaming strings, various dialog settings, etc. just don't make sense to merge. Others like Keywords, Caption Writers, Photographers, Cities, States, etc. which are lists of items can be merged.
You really only have one choice, to replace or not. If you think that the settings stored in your exported file are better than the local settings (which just may be defaults if you've just started anew) then choose to replace.
Also, it seems that other settings are stored under AppData (I'm on Vista), such as the saved preferences for the Ingest dialog. I can see .snap files under IngestDialogSettings and IPTCDialogSettings. I presume I can just copy those across to the new folder?
Yes, but they should be stored in your exported settings file if you chose to export everything. You can always backup the folder(s) so if you don't like the outcome you can restore them.
-Kirk