I have no experience with Ravenbrook MPS. But from the documentation it appears to contain both tracing garbage collectors (automatic memory management) as well

I have no experience with Ravenbrook MPS. But from the documentation it appears to contain both tracing garbage collectors (automatic memory management) as well as manual memory managers. Not dealing with refcounts implies using a tracing garbage collector. There is a wide range of literature out there about such a comparison, but in general I cannot compare the two at all because of the vast fundamental differences.