Is there a possibility, that, when you update an existing dat-file to a newer version, ClrMAME could do some kind of a "diff" and add all the sets, that are new and/or changed to the Fast Scan operation? So if you use the scanner, you don't have to rescan everything, when just one or two sets have changed.
Woudl be like you run MAMEDiff by Logiqx and than use the mamediff.dat, but everything done internal.
I could imagine, that deleted and renamed sets, would do a major problem and...well...I don't think it's easy at all. Just curious...