I used to fly AS532A2 more the 6 years
We wear flying over gulf see at night for hoisting rescue divers most of our work was in hot temperature , mostly more than 36 centigrade, and near calm wend, although we don't use RPM plus
From my experience using RPM+10 produce more drag on the rotor disc and effects the proficiency of helicopter movement OGE,
So I don't think it's good Idea to use RPM+10, during hovering out of ground effect