Swopped 7A collector to 7A MLC on 2 of my T9 miners, 15 collectors + 3A Prospector, very little if any waiting time before moving onto next rock.Cargo space and limpets is a trade-off, but in my build I already had a 3A Collector controller where I've now put the MLC, so my cargo space hasn't actually changed.
One occasional problem, a couple of times the refinery (4A) has overloaded when mining very high percentage metallic rocks, basically it has filled all the bins so fast it has not processed the material.