I don't shoot m4/3 because of size

Undoubtedly true, if you are an "action shooter". For the rest of us who don't need it, it's a moot advantage...

Sorry to disagree, but every manufacturer (of photographic equipment) never offered a great range of lenses, both zooms and single focal, dedicated to the APS-C system - you can also include third party here - Instead always suggested some choices among the respective FF offering...

Many of us had/have both systems - FF & APS-C - but it is rather cumbersome, inadequate (in terms of weight, size - and IQ, I dare say), and why not say it, specially out of "photographic context" to put FF lenses on a APS-C camera!

...And yes, for the mFT system, you already have much more bodies and lens choices:

Bodies: Lots of choices, and compatible with all the available range of mFT lenses!

Zooms: Everything from 14mm to 600mm (35mm equivalent) at f2.8 to 5.6...

Single Focals: From 16mm to 75 (35mm equivalent) at f1.4 to 3.5, and growing...

Thus, with an IQ reaching (or in some minor cases, surpassing) the APS-C siblings, with obviously size and weight advantages when you think - holydays, weekends, hobby, etc. - who, actually, will opt for the more cumbersome system?

Not the majority, I guess, unless you are, mainly, an action shooter!

Having said that, please have in consideration that every new mFT camera generation is showing real improvement on focus capabilities, while the other systems (APS-C & FF) are - more or less - at the same stage they were (some years / models) before...

At least for me, and thinking about prints to A3 (sometimes A2) size, the mFT system is more than adequate for my photo work flow and needs - For better results, FF is the only way I see; APS-C, is for the "IQ Time Being", out of the equation... YMMV

Best regards,
Pedro