I believe that in this case an emulation would be the bigger risk because it would be sufficiently obscure and could pretend to be friendly for a long time while secretly strengthening its power.

Perhaps, though if we can construct such a thing in the first place we may be able to deep-scan its brain and read its thoughts pretty well - or at least see if it is lying to us and being deceptive.

IMO, the main problem there is with making such a thing in the first place before we have engineered intelligence. Brain emulations won't come first - even though some people seem to think they will.