Interesting,
catandmouse. I'm in the same position and have wondered what if ...
For China, there's a definite advantage in using my Swiss passport (except I forgot last time
). Single entry visas cost $20, but $30 for UK and US passport holders, for example.
Within most of Europe (and at insecurity at US airports), I only use my Swiss ID card - conveniently wallet-sized and WITHOUT all the dreadful superfluous info to be included on UK ID cards if they ever get off the ground.