Ananda
The Bunker Group
I do suspect similar thing. As the 6th boats of the class of 6, I suspect the condition on Perle reactor is better than Saphir. More over, Perle with Amethyste are two of the class that from beginning being build with Amethyste improve silencing standard.As second of the Rubis class (but first to be decommissioned) was there an issue with the propulsion system (including the reactor) which makes marrying the undamaged propulsion from Perle with the forward section of Saphir simpler/cheaper.
Eventough Marine Nationale never fully disclose what they're doing with the program (understandbly), I read several analysts that suspect beside changes in hull shape (especially in front) they suspect some adjustments in reactor possibly been done also.
Marine Nationale put Perle on extensive upgrade, shown that they're planning to make Perle as the last of Rubis class being replaced.