I suspect the primary concern ref the son of Collins isn't that it will be more trouble than its worth but rather it will be perfectly good enough and seen as an alternative to the SSNs by a future government.
Australian governments have form in doing this. The ANZACs were a perfectly fine patrol frigate that could be upgraded into a decent GP type but because it was there it ended up as an excuse not to replace the DDGs and now is being stretched far beyond its planned economical life. The FFGs were perfectly adequate ASW ships with a reasonable AD capability but they ended up being substitutes for DDGs.
Army wanted SPGs but instead received extra towed 155mm because the political classes saw them as perfectly good enough. That is one of the ADFs greatest concerns, that their interim, options are seen as good enough, or worse, near enough to what they actually need, resulting in them not getting the capability they actually need.
Son of Collins makes a lot of sense, but could easily become the "good enough" alternative to the SSNs, leaving the RAN with a sub that, while an excellent gap filler and supplement to SSNs isn't as good as the Attacks would have been. End result, the RAN has no SSNs and a design more limited to what they would have had.
Australian governments have form in doing this. The ANZACs were a perfectly fine patrol frigate that could be upgraded into a decent GP type but because it was there it ended up as an excuse not to replace the DDGs and now is being stretched far beyond its planned economical life. The FFGs were perfectly adequate ASW ships with a reasonable AD capability but they ended up being substitutes for DDGs.
Army wanted SPGs but instead received extra towed 155mm because the political classes saw them as perfectly good enough. That is one of the ADFs greatest concerns, that their interim, options are seen as good enough, or worse, near enough to what they actually need, resulting in them not getting the capability they actually need.
Son of Collins makes a lot of sense, but could easily become the "good enough" alternative to the SSNs, leaving the RAN with a sub that, while an excellent gap filler and supplement to SSNs isn't as good as the Attacks would have been. End result, the RAN has no SSNs and a design more limited to what they would have had.