Advise for China trip

Hi,

Currently preparing/planning for a 3 week trip to China in spring and would much appreciate some advise regarding the gear to take. I own a Panasonic G7 and an Olympus OMD10 as well as a canon G7x. I use the G7 with the Panasonic 14-140 mk2 for most daylight shooting due to the versatility this combo offers. In low light I use the OMD10 with the Panasonic 20mm and Olympus 45mm due to smaller size and the Olympus image stabilization, while also carrying the Canon G7x for the convenience of the zoom.

Given that the trip to China is a rear event and the fact that I really like the output of the primes but I much prefer the convenience of a quality zoom (not keen to change lenses while out and about) I am now considering buying the Panasonic 12-35 . I have hired and tested the Olympus 12-40 which is excellent and maybe slightly better than the Panasonic but also bigger so i feel the pana would be better.

The 12-35 is not a cheap lens so i wonder how much better this is in terms of sharpness comparing to the Panasonic 14-140 mKiI .

If in this trip i just take the 12-35 lens and the primes (for night shooting) would I regret it given the maximum focal length is 70mm comparing to 280mm for the 14-140. Has anyone used this two lens pairing on a holiday? What was the lens you used most?

I have been also struggling of whether I should take just one m43 camera (with the g7x as back up) , I really enjoy shooting with the OMD10 (maybe due to the shutter sound and build quality... ) than the G7 which is still a very good camera with more manual controls, a lot more futures including 4k photo video but more importantly better subject tracking where I find the OMD serious lacking , feels a bit plastic though.

G7 of course has no image stabilization so that is an issue for low light shooting with the non stabilized primes and the newer version G80/G85 too expensive to buy now although a possibility later next year when the price has come down but unlikely to be cheap enough by the time of this trip.

Any thoughts more than welcome.

Thanks