I no longer require an offshore investment account - however I previously opened an account with Internaxx (google them) and transferred money across to them at various stages from SA Bank's - it allows direct exposure to multiple international markets at a reasonable price (but certainly not the cheapest). I can highly recommend them.
Note however, the account was opened in a different era, where local product providers did not over reasonable offshore packages. today - I would take a serious look at the local offerings and in particular the Easy Equities option. So yes, I'd say go ahead.
ps. although the acquisition of Mercantile by Capitec has been announced, sale has not yet been completed. So Mercantile is NOT a subsidiary of Capitec.