"Of course, all of this would be much easier over a beer"
A man after my own heart.
Yes, FAR part one, definitions. At least as defined by me. Unconventional for purposes of this discussion is meant to describe the aircraft not the mission. Though somewhere the two cross.
"Had AFSOC been in a position to begin the program, it would have been a different size"
Agreed. However had the design been locked in larger or smaller driven by AFSOC needs, IMHO the Marines wouldn't have signed on but rather pursued a traditional rotary wing replacement for the phrog. Where would that have left a small component of the USAF? Again, my opinion, but Cheney would've successfully canceled the program in it's nascent stages. Something he tried but failed to accomplish.
A clean sheet medium lift transport is a utility player while an aircraft designed for special forces is a position player. (I know these sports analogies drive the Brit's looney) That said, the US military has a wealth of experience in converting trash haulers to suit the needs of special forces. Yours is the first that comes to mind, many others follow. How many special forces aircraft have been adopted for utility roles? Not going to say none, but I'm hard pressed to come up with one. I'm hard pressed to even name a major aircraft acquisition driven by the needs of any special forces component of any branch of the US military. It's late at night so there may be some escaping my fallible memory.
The Marines need a utility aircraft designed for their needs, not one compromised from a special forces application. An aircraft equally at home hauling Marines into a LZ, landing in a CAL site or maneuvering around the deck of a LHD. The AFSOC surely thinks the same, but the Marines are the ones who had the political wherewithal to power it from a paper airplane, through painful crashes, political turf wars and now to fruition
Either one camp or the other is going to feel overly compromised. The question is which operator is more able to work within those compromises.
I've made my argument as to why it shouldn't have to be the Marines.
I'd be interested to see the views of the other bit players who plan to or contemplate operating the aircraft.