I admit to not knowing much about this programme but I do recall, in 2003, finding myself working with a chap who had recently transferred from the IPT. I had the same debate with him over the options and he stated, categorically, that converting the ship to whatever system was a "nil cost" change, so what they chose to contract was immaterial. I was gobsmacked but you hear crap like that every day.
A couple of years earlier the same IPT had, theoretically, FOAEW under it's wing (the replacement for Sea King ASaC). The man in charge was recruiting staff and rejected ANYONE who claimed related knowledge on the grounds that "AEW/ASaC are in no way related to FOAEW", despite the costing a assumptions dictating re-use of the ASaC mission system (itself a flawed assumption).
Just a comment on the general level of competence I experienced at the time. It was difficult to imagine who was worse; DEC for assuming the above or DPA for blithely accepting the programme based on such assumptions.