I am not authorised to give financial advice etc etc but I think that it makes sense to have a substantial fraction of assets (but not all) where you live or correlated with its market, especially retirement funds. So I moved mainly from the US to UK for simplicity and speed, but I may push some of that away into non-UK markets when I muster some enthusiasm.
If you are in the US then maybe markets correlated with the US but not the US (Canada?) may be a sensible alternative.