Here’s a nice write-up by someone who went through a similar process as I’m going through right now and switched from Nikon FF to the Fuji X system.
Here The Online Photographer has an interesting discussion of sensor size and how it affects image quality, don’t miss the comments which are also full of interesting tidbits.
Here’s a Photography Life article on Micro Four-Thirds VS DSLR.
Here’s a test by The Wandering Lensman: The Practical Difference Between Full Frame and M4/3
Another interesting comparison: Printing Large Photos – A Comparison of the LX100, GH4, and D800
Here’s a discussion by Michael Reichmann on the Full Frame Myth.
And finally, a great discussion by two highly respected photographers on image quality in the digital era and “when is ‘good enough’ actually good enough?”