Well looking at the last 10 years, it clearly favors the US stocks, but nobody knows what the future will hold. I personally have gone for an allocation roughly like this:
35% SPI Extra
35% World exCH
15% Small Cap World exCH
You can drop emerging markets for US if you want.
Only cash is insured up to 100k that is correct.
The actual shares themselves under swiss law are segregated and held in your name. (in the case of VIAC they are held at Credit Suisse)
In case the broker goes bust, technically you should get access to your shares so no insurance is necessary. see here for the source: https://www.esisuisse.ch/