Buckfast vs local mongrels after four winters — my October decision on which queens get replaced next spring

Flanders, six years, fourteen colonies, and for four of them I've deliberately run a mix: six with bought Buckfast queens and the rest headed by queens raised from whatever my own colonies produced, mated locally with the local drone population. The Buckfast colonies are calmer to work, build up fast in spring and produce more honey in a good year. They also eat more feed getting to winter weight and two of them were the first to look miserable in the wet February we had. The local mongrels are less predictable — one was genuinely unpleasant and got requeened — but as a group they overwinter on less, they shut down brood earlier in autumn, and their daughters don't fall apart the way F2 Buckfast crosses do. The F2 point is the one I'd emphasise for anyone choosing. A bought queen is a known quantity; her daughters mated with my local drones are a lottery, and two of mine were the worst-tempered colonies I've owned. So my October decision is: replace the two poorest local queens next spring from my best local colony, keep the two best Buckfasts, and stop making F2s.