Most of us probably have the dream of just carrying 1 body/1 lens. That dream of picking up a Round the World ticket, a shoulder bag with a extra set of pants/shirt/underwear/socks and plastic freezer bags with film. Sling that M2/35 or whatever on the other shoulder and go for 3-4 weeks. "Around The World on 80 rolls".
Unfortunately, I used to shoot commercial stuff - everything was duplicated and needed large cases to shift (4x5/Hasselblad/ multiple F or F2's with motors, lenses from ultra wides to longer ones. Flash equipment, reflectors, cables and power cords, flash synch stuff etc. I used to have a beefed up Ford Econoline 250, just to shift the stuff!
I consider it being a vast improvement to be able to carry what I need in a small fishing bag (and so does my back!).
The R4M Bessa is a recent addition (2 years +) to the package - it is used in lieu of carrying multiple finders. It can be used with 21/25/28/35 without a problem and even the 50 works, though smallish. For the last year it has had the 21f4.5 ZM Biogon stuck on it and it is usually paired with either the 28f2 Nokton or the VC 28f3.5. My M2's have 35's on them and the M6/MP takes care of the 50 and/or the 75.
We are heading to Japan for a week towards the end of this month, and that will be 21/4.5 and 28f2 on the R4, M2 with the Nokton 35f1.4 and possibly the R3M for the 75 and 50 (it has free standing 75 frames which makes it easier to use - no "mix" up as with the M6/MP). Not a small package, but it is portable, even for long hikes through cities.
OK. I am still dreaming of that kit, the M2 and a 35 and bags of Tri X!