I am getting a bit of traffic discussing the next-generation Australian subs and the comments section doesn't allow for a detailed response.
On last comment that suggests that nuclear power equates to the 'best possible option'
is so clear cut an answer.
The repeated penetration of the USA's carrier ASW screen in RIMPAC exercises by the Collins class SSG, showed the Americans not to sell short the capabilities of a modern SSG.
So much so they got their collective nickers
in a knot and hired the Swedish equivalent to come up with a successful tactics to stop the Aussie boats.
Their answer was to cheat in follow-up RIMPAC exerises. That should be enough to say what results they got from their study of the Swedish SSG.