I would love to be a prime lens shooter.
One of the advantages of MFT is the small form factor of all their lenses, meaning toting your version (and there are a few ways now) of the holy trinity* is a completely different experience to the full frame shooter.
Two of the trinity compared. The 14-24 is heavier than both of the Leicas together. To be fair, the Oly 7-14 and 12-40 Pro are the true equvalents, but there would still be a massive weight advantage to the MFT pair.
The only area the MFT format falls behind apart from depth of field control, (which has advantages in either format), is in low light. The light at the end of that relatively short tunnel, is that the added depth of field MFT offers, means you can shoot 2 apertures wider for the same depth of field at the same subject magnification.
This means in real terms, you can use a faster lens and because of the MFT sensor to lens advantage, actually chosen with lens design in mind, there are plenty of cheap, fast and high quality MFT lenses out there.
They are of course, prime lenses, because regardless of format, zooms faster than f2.8 are vanishingly rare, with literally only a half dozen available (2x Sigma f1.8’s and 2x older 43 Oly f2 lenses come to mind, but I may have missed a couple).
The power of a 90 f1.8 equivalent in MFT. Plenty of depth of field, sharp wide open and long enough for this shot, all from a lens the size of a nail polish bottle and one at the cheaper end of the range.
I shot with a full clutch of fast primes in Canon full frame**, but the weight of those “L” lenses was prohibitive (read, generally a pretty shitty experience). I tried the beast lenses on dinky cameras with some success and kept my choice limited, then switched back to f4 zoom lenses on 5D’s, but at the end of the day, I had either speed or versatility, but not both and never with a major weight dispensation.
In MFT, two cameras with a handfull of primes is a real kit possibility. Even a three camera kit would be ok (EM10 Mk2).
F1.8 on MFT, which is f3.4 on a FF. Shallow enough for separation, but not so shallow as to be impractical.
I have (in full frame terms) 30, 35, 50, 90 and 150mm covered at f1.8 or 1.7 and 60mm at f1.4. The missing link is a wide and the Leica 9mm (18mm) is on the way. A 24mm equiv would be nice, but a highly corrected 18mm will be safer and as useable for those times when genuinely wide is needed and I do have 12 (24mm) covered several times now.
My core would be the 9 (18), 15 (30), 25 (50), 45 (90) all at less than 200g each and the 75 (150) at about 400g. The quality I can get means I can crop by half or more, so in real terms, so I have effectively 18-300 or more covered, all at f1.8. With a G9 and EM1 mk2 the whole kit would come in at less than 2.5kg. This would also mean I would be able to get away with a little flash like the one the EM1 came with or a small LED.
To be honest, the 8-18 and 40-150 f4 do not add much weight, but they do lack speed for the many indoor horror stories I have to deal with, so I still need a couple of primes.
The other advantage of the 9mm would be for times when the 12-60 is the logical main lens, but something wider may be needed, meaning I still have to pack the similarly sized and largely over-lapping 8-18 just in case. When shooting sport with long lenses I often have to do a victorious team or locker room shot at the wider end. Both these zoom lenses take up substantially bigger spots in a bag than a prime. The 130gm 9mm could be shoved into a jacket pocket, rather than a separate bag.
I could even switch back to a slim-line Domke F5c, which is perfect for a small lens kit. It has room at the top for a couple of cameras with mounted lenses, an opening in the lower front for 3-4 small primes (just avoid the F5CX weather proof, which does not have the front pocket) and two flexible 3-part dividers. This bag, one of my past favourites, is so small, it could be accused of not being the real deal.
Alternately, I have several satchel type bags (Tokyo Porter, Crumplers and Filsons) that could work or the pending F3xB, that could now take a 2 lens divider (that won’t fit bigger lenses).
*Wide, standard and long f2.8 zooms, which replaced for many older shooters, the tight four of a wide (20-24), semi wide (28-35), short tele (85-100) and longer tele (180-200) of the pre zoom era.
**24 tilt/shift, 35 f1.4L, 50 macro, 85 f1.8, 135 f2L, 200 f2.8L and 400 f5.6L. All lovely lenses, but all heavier than anything I would carry now in a prime that did the same thing (except my 300 f4).