i think that it really depends on what you intend it for... if it is to be a back-up, a 2nd body, or a 2nd system. from your question, it sounds like you're asking about a 2nd system.
i'm a proponent for using the first tool for the job... so to that end, it really depends on what you like to shoot. i personally have 2-3 systems, and often have a headache of which camera to bring out...
that been said, if you really want to get intimate with RF, i think that you have to "force" yourself to shoot with RF for a while... learn what you like about it, and what you don't like so much. how it works for you in certain situations, and how it can pose some challenges in others... and learn how to really use a RF camera.
along those lines, some of the RFers here carry 2 RF cameras, one 28 other 50, one b&w other slides, one digital other film, etc. others may bring a film RF and a digital compact or mirrorless (with M-mount adaptor), e.g. GRD, GRX, XPro1, OM-D, etc.