Note, however, that Rosoboronexport is pushing only the Amur 1650, it's only the Italian Ministry of Defence that is pushing the S1000, even though Rosobornexport is a partner.
Unlike the DCNS Scorpene line (Project 75), the second line of submarines will look to purchase submarines with air independent propulsion (AIP) systems as standard. And unlike Rubin's proposed AIP system on the Amur, the Indian Navy is understood to be very keen on the S1000's AIP system, particularly because its based on the Siemens SiNavyCIS BZM-120 PEM hydrogen fuel cell (Figure 3).
The S1000 also features specialised non-magnetic hull fabrication, a feature that the Navy wants in its next line. The HDW U-214 is almost definitely out of the reckoning -- Pakistan is in line to order three from Germany. Also, the Indian Navy is simply not convinced that the Type 214 takes any meaningful advanced technologies from the Type 212/212A of which it is an export derivative.