However big the baggage compartment is, it ain't big enough. When you start carrying Schlumberger hands, the bags eat up the baggage space really quick. In a 412/S76 you're lucky to fit 9, using the rest of the seats for baggage in addition to the baggage compartment. It takes close to 25 cubic ft/man for baggage, sometimes more.
I don't know the max weight of either the AB139 or the S92, but most decks in the GOM are limited to 11,000lb or less. The big deepwater drilling rigs likely can handle them, as long as they have the range to get out >200NM with a load. You won't be able to stop & refuel on the way like you can with the current fleet.