I traveled and used the RX1R and then RX1R II for a number of years as my companion camera to my main system. Wonderful camera with great 35/2 lens and quality & resolution that definitely won’t disappoint.
I’m now back to Leica as my small bring along camera (M10 & 35 FLE mostly) but I realize that this may not be the direction you are looking for. If you wanted a great 28mm fixed camera then the Q is wonderful but I wouldn’t shoot people with it normally.
If I hadn’t gone to Leica as my go to small travel system or companion camera, I’d still have my Sony RX1R II.
Agree with much of this. Am in love with MFDB, the back and the wonderful lenses on tech cameras. Moved to an Alpa STC to get it smaller for traveling. Regardless of what camera, the back itself weighs a bunch - and by the time you have it on something, with a lens, its a 4-5 lb thing. Add some batteries, another lens, tripod and head, charger, etc. and it adds up.
So what makes a good portable second fiddle? Not clear. I've used the RX1 for years, and its an infallible workhorse - very good for photographing tech'l drawings in archives (a passion) under horrible conditions. The lens is so good you can do anything with it. Its hard to think of a situation where it doesn't work well. That said, I strangely find working with it to make "art" photos. it seems more to document than to inspire. I don't know why - possible its just a bias, or perhaps the color tones of the sensor.
Have tried a few Leicas - MM and M240. While the MM is magic, the color with M240 is appealing. Rented one and found it quite workable as a walk around camera and also in a museum to document art. It might just be that the Leicas have viewfinders and the RX1 has its screen that is the difference.
All to say that there is a need for a smaller camera to accompany MFDB, or use on lightweight trips; its not clear what is best, as nothing is as nice as a big sensor and superb lenses; its a personal choice and a combination of user comfort, large resolution, good colors, and a good lens. I lean to the Leicas due to the optic quality of their lenses and smallish size but know that no M series camera is as easy to use in poor conditions as the Sony. Maybe the Q with a 35mm lens, or the new CL would work too. Some hope that the Hassy XD1 is an answer.