This gentleman has an interesting view on M4/3.    Must admit I'm a bit of an Olympus fan boy (apart from the droolingly lovely Leica D-Lux, which is also M4/3), seeing as I still use their 1970s film cameras, but I think comments actually relate to any non-full frame users of other makes. Easy to say spend mega bucks on pro lenses, but these days general lenses are pretty good.
https://www.youtube.com/watch?v=CFGEqzeFvIU

Must be a caver. He has got the earrings so you can nail him to a plank and drag him out should he need rescuing.