From an engineering viewpoint is it easier to redesign the central fuselage (S-3) or in the case of say C27J from a single conventional vertical tail assembly to which the C-2A Greyhound has four vertical stabilizers and folding wings. As I said before the hanger on a US Nimitz class carrier is 7.80m, S-3 Viking as it stands is 6.93m C27J is 9.64 and the C2-A 4.85m and V-22 6.73.
Payload and range distance is another matter altogether between the different aircraft,
S-3A. Six passengers or 2,120kg of cargo, Range 2,765nm (5,121 km) how this changes with the new airframe I don’t know
C-2A. 26 passengers, 12 litter patients or 4,536kg cargo, Range 1,300nm (2,400km)
C-27J. 60 troops or 46 paratroops or 36 litter patients or 11,500kg cargo, Range 1,000nm (1,852km) with 10,000KG or 2,300nm (4,260km) with a 6,000KG payload
MV-22B. 24 troops (seated), 32 troops (floor loaded) or 9,070kg (internal) 6,800kg (external) cargo, Range 879nm (1,627 km)
But it appears from this article
http://www.seapower-digital.com/seapower/august_2013/?lm=1374555966000&pg=36#pg36 (thanks Colay) volume is more important than weight which can be appreciated from RAAF view point to the selection of C27J over the C295. From Delivering the goods: the ADF’s future battlefield airlifter by Tom Savage and Andrew Davies,
“The C-27J is more expensive per unit to acquire, and has a higher hourly running cost, but has a larger fuselage with the ability to easily fit some of the larger items the ADF will want to move intra-theatre, and is more compatible with pallets from the larger airlifters. It also offers better performance in terms of speed and time to height, both of which contribute to greater survivability in low-level threat scenarios, as well as meaning less flying hours for the same distance. As well, the ability to move some of Army’s light vehicles is a plus. Given the small number of BFAs to be acquired and the limitation to a single light vehicle per flight, the extent to which that capability should be weighted is debatable, but having the option broadens the mission choices. The C-27J thus unquestionably offers superior operational flexibility”
http://www.avia-it.com/act/rassegna..._Analysis100_future_battlefield_airlifter.pdf
The US already has if my information is correct 27 aircraft operating in the US and 16 new build aircraft went straight to the bone yard might as well make use of them if they can.
http://www.military.com/daily-news/2013/10/07/new-air-force-planes-go-directly-to-boneyard.html