Raid 1 is now generally considered to be good for protecting you against downtime due to the vagiaries of disk drives and will protect your most recent files that may not have been backed up. But a power surge will quite probably take out both drives so of dubious merit on its own.
Don't use online backup as your sole form of backup as what would happen in the event of bankruptcy ?
I reiterate that an external drive is a good start.
Advocating a more expensive and complicated system to someone who currently has none may simply discourage them from trying. Save the more advanced stuff for those already doing some backing up and asking about more advanced solutions and therefore more inclined to invest time and money.
In the twenty years I've lived on a street with more than 100 houses on it there's only been one fire and that was a shed
