Frankly, this is a terrible comparison because you're comparing a 24-50mm zoom with a 28-84mm equivalent. That's where the M43 system wins out: "long" lenses that are nothing like as long as their full frame equivalents. The bodies will always have certain size limitations for batteries, electronics, ergonomics and the like.
Well, only the 2 top-end Panasonics have a 25mp sensor (G9II and GH7). No OM models which have come out subsequently have been above 20mp. I would say 20mp is very much still the standard for now. It remains to be seen how those 25mp sensors could behave in a smaller camera body (heat dissipation has always been a bit of a concern with Micro 4/3 sensors when tech advances. Bigger size means easier dissipation and better heatsink abilities. Hard to know if they could implement the 25mp sensor in, say, a GX9 II body without running into problems.
A couple of years ago, I went to Greece with just the E-M5ii and 12-45mm f4 Pro, and a Ricoh GRIIIx. The light weight and small size was a dream. I did end up wishing for more resolution than 16mp. My next trip, I don't even own Micro 4/3, so it's going to be a Pentax DSLR and a few lenses. I may regret it!! But at least I'll get more resolution for pulling the details out of scenery.
Did you read my concern before getting on high horse ?
I wasn't on a "high horse", just pointing out that you're comparing apples and oranges. I've got no skin in this race - my other half uses M43, but I'm happy with my M240 - but it seems that every lens in the M43 ecosystem is much smaller than its full-frame (and even APS-C) equivalents.
Correction:
As a m43 shooter I hate to say it, but for some types of lenses, getting the equivalent to full frame in m43 can cost more and result in a larger lens.
As a m43 shooter I hate to say it, but for some types of lenses, getting the equivalent to full frame in m43 can cost more and result in a larger lens.
For example, I just picked up the Pana Leica 12mm f1.4. It's a beautiful lens with excellent build quality and IQ, but it's expensive and fairly large. For less than half the price, one could get a Sony 24mm f2.8 semi-pancake and have the advantages of Sony's full frame sensors. And the lens is also half the length and weight.
Similarly, the Olympus f1.2 primes are uniformly sizeable and weighty, and cost around $2000 AUD retail. They have beautiful IQ and build quality. For $1000-1500 one can get Panasonic 35/50/85 f1.8 lenses that are faster, weigh slightly less, and are roughly the same size. They lack the manual focus clutch and build quality of the Olympus Pro primes, but they have the advantage of full frame sensors, and have excellent IQ.
The size advantage is in lenses is outside of those parameters, where you want the smallest lenses possible while maintaining a reasonably wide aperture.
Oly and Pana f1.7/1.8 primes are similar in size to M mount lenses and half the weight or less.
The Panasonic 35-100 f2.8 gives you the reach and constant aperture of at full frame 70-200 in the size of a can of Coke.
A Pana or Oly 100-400 is slightly smaller than a Canon 70-200 f4 and gives the reach and range of a 200-800mm full frame lens almost twice the size and weight.
There's always the tradeoffs between full frame and 43 sensors in terms of dynamic range, aperture ranges, depth of field, size and weight. It's up to the user to determine what is most important at any given time and situation.
Why do you say indoors? I'm wondering because I see a variety of different lenses of speed, size and focal length available, AF and MF.
As you surmise, an f/stop is an f/stop regardless of lens focal length or the format the lens is going to illuminate. This is because the light gathering power expressed by an f/stop is normalized by the division in the expression, that is "f/2" means "focal length divided by 2" in long hand which specifies the aperture opening diameter in whatever units it is being calibrated to (usually millimeters), so f/2 with a 50mm lens means an opening of 25mm, f/2 with a 100mm lens means an opening of 50mm, and f/2 with a 25mm lens means an opening of 12.5mm. It turns out that the light transmission through a lens is always consistent and linear with respect to the ratio of the focal length to the diameter of the lens opening, which is why this system works so consistently ... thus f/2 with all three of those focal lengths transmits the same amount of light per unit time.
With all due respect to Ctein and you, the specific notion that I suggested in my example above (a 35FF 50mm f/2 lens on 24x36 vs a 25mm f/2 lens on 13x17.1) are definitely "equivalent focal lengths" based on comparing the field of views on the different cameras, and the exhibited DoF that each camera/lens combination creates shows that an equivalent aperture on the 35mm format camera to match what you get with the mFT camera would be about two stops different. The numbers show it clearly.