Micro Four Thirds format is a curiosity to many, a guarantee of inadequacy to some, but a well kept secret to others.
I have not had any issues getting the images I need under pretty much any conditions with the following things taken into consideration;
Lenses are the secret. They are the power of the system, but are also the main requirement for best quality. this is the same with most formats, but the difference is the main thing to pay attention to and comes with a vastly reduced stress element. You need great glass and without breaking your bank balance, back or sanity and you can have them.
A 150mm f1.8 is a dream lens for a full frame user, but for M43, it is only a very well corrected, regulalry priced and sized 75mm f1.8. Yes you can crop the full frame camera, but all that would be achieved is an equal pixel count or maybe even less and do you need to?
Processing helps. Just running M43 through Adobe processing is ok, but to get the best out of the system, look elsewhere. Again, like lenses, this goes for all systems, but for Fuji and M43 especially, because Adobe does neither any favours, use a hungry competitor.
When I used Lightroom, the constant battle of sharpness vs noise was tiresome and limiting. In Capture 1 this became a near irrelevance, with ON1 No Noise as a sidecar addition, it effectively disappeared. I almost never see that “grittiness” so common with Lightroom from ISO 1600 or above and can confodently use ISO 6400 expecting good results, 12,800 even with care.
Be confident, realistic and aware. The call of full frame is strong, but do the math, look at things realistically and use the gear without reservation. Can you afford a 600 f4? If not, can you accept that a very good 300 f4, doubled by the smaller sensor, can actually give you 20-26 very sharp mega pixels of quality, that are in real terms indestiguishable to a full frame 20-24mp. Full frame systems emerging are starting to tackle the same thing backwards, providing us with slow 6-800mm lenses at a budget price, but sacrificing 2-3 stops of light. What is the difference, apart from the maturity of the Olympus and Panasonic systems and the real benefit of actual light gathering for the reach?
Embrace the benefits. The added depth of field, smaller size lens to reach/speed dynamic and the easier lens design advantage are strengths not weaknesses. F1.8 that acts like 2.8? What is the problem. In most practical situations, more is more. M43 was designed for a few reasons, not the least of which was lens design.
To make better lenses, one must either use a smaller sensor (smaller image areas are easier to make good glass for) or use a larger mouth to image surface area, like the the new Nikon Z mount. The M43 format is smaller, but squarer also, which helps.
Ever wondered why Sony needs to make huge front elements for their fast lenses, when Olympus or Nikon can make relatively tiny ones? The main reason is the ratio of lens mouth to sensor size. The Sony “mouth” is smaller than their actual sensor diagonal, the M43 and Nikon Z ones are larger, meaning full coverage of the sensor is easier to achieve.
In some cases, they can do the seemingly impossible. The f2 zooms from the original 4/3 system, the 9mm f1.7, the 10-25 and 25-50 f1.7 zooms. The average size to lens speed are all M43 benefits.
The advantage of gathering f2.8 light, but shooting at effectively f5.6 depth means misses are less brutal and less common.
Super shallow depth of field is fine for effect, but from a professional perspective, more is more. Try telling a pissed editor that you were looking to show of the beautiful Bokeh of your lens when half the subjects face is out of focus. Realistically, f2.8 is as wide as you need to go, but retaining f2.8 from f1.8 light gathering? What an advantage.
Smallow depth is still easy to achieve, but it is not a liability.
Recognise “enough” when you see it. We are all after great quality images and sometimes forget when viewing at 2-400% on a screen, that we usually have more than enough and that skill and application are the true measures of quality, not obsessive pixel peaking. To me, a pin sharp, fine art grade 12x16 print is the standard I aim for.