I have been eagerly reading about the small cells, wondering whether I can convert my bees in time for the arrival of varroa.
Small cells cannot help you. It is not that easy. You just loose your hives.
I have had varroa 20 years. There are good cures against it. Here is my 3 of my hives and they forage well with their mites. http://bees.freesuperhost.com/yabbfiles/Attachments/valmis3.jpg
"Smaller honeybee cells neither reduce the reproductive success or the amount of cells infested by the Varroa destructor mite, according to a New Zealand study.". http://www.bee-l.com/biobeefiles/pav/scstudy.htm