Thanks sam0t
Yes that Opus button for going into Admin mode temporarily is a brilliant idea.
I agree with jon's advice not to run Opus as Admin (i.e. with elevated permissions), except temporarily for particular jobs, which he explains very well here:
[Why NOT to run Opus as Administrator under UAC)
I know some people get annoyed by UAC prompts and turn them off completely for the whole system, but personally I find those occasional prompts quite reassuring - that the system is watching out for potentially dangerous actions.