That article is wrong on so many levels, and in ways that I really despise.
For example: condescending arrogance -
"On the one hand you have prominent photographers like
Trey Ratcliffe who are opening shelving their full frame Nikon systems and switching to more portable Sony NEX systems. The claim is that the image quality is good enough for his purposes and that the freedom afforded by the weight and bulk savings makes photography life so much simpler as to negate the downsides of a small sensor. In Trey's case, a man who spends more than half of his life traveling and who's main outlet for images is web, I don't doubt for a minute that it's a good choice for him. For now."
Trey is an extremely popular photographer who knows how to promote himself and his vision, clearly loves what he is doing, and he uses whatever gear he needs to to get the job done. He's used DSLRs in the past and has used various mirrorless cameras as well.
To condescendingly suggest that mirrorless is good enough for him now, because as he grows as a photographer he'll see the error of his ways and move to a larger format is just incredibly arrogant.
Then we have:
My main problem with all of this is that I am a lens man. I put my money in lenses first and cameras second. Good lenses have the potential to last a whole career and some of the best hold their value incredibly well. When I buy into a system I want to invest in a set of top quality lenses that are going to last me a very long time. Right now I simply can't justify doing that with any confidence. Zeiss have a pair of lovely Touit lenses for Fuji and Sony systems but if Sony go full frame in September that would be money well wasted on those Zeiss lenses because you can guarantee Zeiss will make FF versions and then the value in the originals is all but gone.
For me, photography is about getting the tools to do the job, not about investment as such. This kind of thinking is an anachronism in a era when lenses are so complicated and require hardware and software compatibility that they will have a very short lifespan compared to lenses in the past.
He's correct about the Canon system being weak, but neglects to point out that this is probably intentional (classic Innovator's Dilemma) and he may have a good point about the Nikon approach to marketing.
He makes it clear that he has no plans to invest in m4/3 so little first hand experience. He's a creative professional who likes his FF cameras and seems to have a hangup about justifying that; but m4/3 may well suit others who have different requirements.
No need to slag it off just because it doesn't meet his requirements.