I'll have to take your word for it that you 'know quite a bit about them' CAC, but my understanding is that it is the electronics and airframes that need replacing and that much of the other equipment can be swapped over (Boeing named the engines as one of these parts, but maybe the particular chap I spoke to wasn't up-to-speed on the RTM). Are you saying that the current airframes would be reused, and the engines discarded?
Well I'm not in the know as to what the decision will be, I was just stating what I feel we should do. RTMs were leagues ahead of the T700 when we first procured them but the T700s have been developed to the point where they are at least as good as the RTMs. By having our own software on the aircraft means we are alienated from the US software updates (which they get for $25 an update... yes I mean $25). Whatever way we go, completely new aircraft or modify ours we need to go the FMS route as I hope we have learnt our lesson by having a bespoke aircraft.... we shall see!