Particularly these two matters:
Higher submerged speed - evasion once detected or fleeing after delivering payloads (mines, spy AUVs etc.), yet contradicts the silence propulsion while doing so and only to be used when submarine is "detected", or when the crew believes they are detected.
Eliminating snorkeling, it is done frequently and not really a cool event, the sub can neither cease it immediately and dive, if caught, and it is necessary for the batteries.
Plus batteries are not cool, heats up and constantly cooled if loaded heavily and generates gases (particularly at high speeds).
Does it worth the bang? I am not sure too, it is currently just a plan ahead of Milden. We first will have Milden-I, then Milden-II and maybe lastly what they call as "Nukden". Officially circulating with the high command so they have it in the long term plans since awhile ago, but "long term" here is crucial. Probably referrring to 20+, 30+ years from now.
And i am assured at those dates SMR's will be something similar to submarine diesel engines which you may plug and go.