Perhaps EMS has different costs associated with it than Offshore O&G, but ask CHC (if you can find anyone left!) which is cheaper to operate, a 76C+ or a 139. It ain't the 76. Years of operating them side by side on the same base proved that.
I do realise that an A/A+/A++ is not a C+, but if you match performance with DOC's, it is hard to beat a 139.