When will you travel? On another forum someone mentioned that YYE is around 4 months wait currently - you may want to check.
If you can wait that long, you may as well just use the camera and see how it checks out.
If no issues, there is no need to send it in for service.
I don't personally believe in the "cult of CLA". If nothing is wrong, don't fix it, and if the finder is a little cloudy (which is not unusual on an M6 and just an accumulation of dust on the inner surfaces on the viewfinder windows) then just have the top removed and the surfaces wiped by the local guy if he is familiar with opening up a Leica.