Finny,
I used apigaurd. It clearly did not work to the claimed efficacy. Reports from the internet showed up some serious misgivings with both sealed packs and the bulk supply. After getting what was clearly a lower kill-rate than the adverising claimed, I read the testing regime (the small print

) which clearly demonstrated (to me) that use in the UK was unlikely to achieve the advertised efficacy claims by the manufacturer.
Thymol was very good as a treatment but required a little more thought than most gave it. At the time I was running plus or minus twenty colonies. Selecting the correct dosage for an efficient varroa cull without killing the colony required rather more attention than the ‘average’ beekeeper would be capable of administering.
One has to remember that, where averages are concerned, there are usually as many either side of that level.