You mean as inserts or doublers, right?
It gets confusing, because there are two meanings for the word "soaker". One is an absorbent layer added to the diaper. But when we're talking about wool, we're actually talking about using it as a water- proof/resistant OUTER cover. So microfiber won't work as a cover, which I think is what Turtlemum is looking for
And Turtle--yes, I believe an ME cover will work over those diapers. I can't say for sure, but MOST waterproof covers work over fitteds/prefolds/etc.