I used to get a decent drop after the OSR was sprayed, very antidotal evidence, but mite loads were always low after.
I don't like Apigaurd, just my own thoughts, but don't feel it's effective. Colonies coming late back from the Heather would certainly gain little benefit and I like strip treatment, whatever is used, to be within the Colonies, not sat on top.
Vaping oxalic is definitely the way forward, alongside something else, but I do know a large beefarmer who only vapes, with very good results
We have a VM on order, which should be here end of summer, hopefully, the bending required to use the sublimox is not helping my back at all.