Update of the update:
Enum typed actions that all the other frameworks use - probably without even wasting a thought - totally do achieve the efficiency I was looking for. Hence, RedCat will migrate to enum typed actions as everyone else does.
I do hope though that the new API remains as convenient as the current one. It was quite liberating not to waste too much thought on which actions a Reducer can consume.
Meanwhile, other features like the general purpose typesafe app dependencies or the dispatch reducer are noteworthy contributions.