During holidays I had two cameras with me: Sony a6000 with Sigma 56mm f/1.4 and Ricoh GR3 (and iPhone).
Sigma lens at f/1.4 or f/2.8 allowed me to take some amazing portraits. This lens is exceptionally sharp, even wide open, although focusing on fast action is sometimes not fast enough on an old camera like a6000.
Ricoh on the other hand has one big advantage: size. Small size means that the camera is easier to carry on (even in a pocket) and easier to pick up. It means that because camera is small and light, I can have it on me at all times, even when I don't take photography bag (or any other bag) with me. It allows me to get extremely contrasty B&W shots. Focusing is sometimes an issue (camera sometimes focuses on the background instead of the subject which is in the middle of the frame) but otherwise it's a great camera. Highlight protect metering mode is doing a great job, however, it has its own limitations: in a scene where there is even a small bright area, camera will make entire scene dark, in order to preserve that highlight detail in that one bright spot. This results in a very dark, almost black jpg, but raw has a wide latitude for processing, so not all is lost. Also, since the camera has physical controls for almost all settings, adjusting exposure is fast and easy.
One thing which I miss is the ability to recreate Ricoh look in Lightroom by processing the raw file.
So, do the cameras complement each other?
In a way, yes, definitely.
Is it comfortable to carry two cameras? Definitely not, however, I don't regret this choice as I was able to make some great portraits with Sigma which would be impossible with Ricoh.
Ricoh on the other hand can produce some amazing shots of beach and seaside, which I didn't have a chance to explore in detail.
Issues: when shooting with Ricoh, it sometimes complains about memory card - to resolve that always have a backup card and if using microSD with adapter, always have a spare adapter, just in case. The card was fine all along, but somewhere along the electric connection there was an issue, causing memory to not be recognized by the camera.
Same goes for batteries: always have a spare, just in case, same applies to a6000.
Good practice: check camera before leaving the house: start the camera and actually try to take a shot, look at remaining photo count and battery - it might happen that even though all looks good initially, when you actually try to shoot, it complains with one kind of an error or another.
Another issue with Ricoh is dust. Unfortunately, the camera is not sufficiently protected against dust, so after a while you will get dust on the sensor. In most cases it's not an issue, but when you shoot high apertures (f/8-f/16) against even background (like sky), you will clearly see all of dust particles on the sensor. It's a shame as it's limiting the camera usability.
