Might be a bit late to move them, they are quite big now. The compost is deliberately gritty with some slow release fertiliser and are in full sun. I will take your tip for next year.
Some colonies in Spring get ahead of others in development. If you take frames of brood from strong colonies that gives them more space and a slower build up thus mitigating swarming, put those frames of brood in to a slower colonies to build it up.
It means that all colonies are roughly equal...