Just for completeness, this all went as planned and finished up a little earlier than expected, too.
It's been a very busy weekend with changes in a lot of places related to updating QSOs and their metadata (like RST values, comments etc) more efficiently. Thanks to you all for being patient if this interfered with any uploads.
Club Log now supports VUCC credits for verifying grid squares (and you can see details of what we've recorded by using the Log Inspector). In due course I will look into adding the possibility of separating DXCC and VUCC grids in the gridsquare map, but for now they are combined.
Changes to existing QSOs are now quite a bit faster and a lot of the murky and more complicated ways that QSOs can change shape have been taken care of in a satisfying (more unified) way using completely fresh code.
There is a background task running which is copying over some info you might see on OQRS labels, such as FT8 RST values. This should be complete in the next 12 hours or so. Although it's quite a simple task, there are 600 million records involved so work on that sort of scale always extends the timings a bit.
A nod to Dave AA6YQ for his quick-fire help with changes and looping me into conversations where I was needed; Marios 5B4WN on the Club Log team, who kindly updated a load of his code last night to clear a few roadblocks; Tom DL2RUM for giving me some great test ADIF files to find some loose ends; to Mek SQ3RX for patiently testing various changes that helped improve the 'merge' logic on ADIF imports, and to Joe W4TV for giving me specific and detailed feedback on his log and grids in the VUCC scheme.