I'll wait until there is another source on this purchase. AFAIK the Chinese have mostly bought licensed production of most of the Rusians Airdefence systems. And thats why they are not copies or as "Chinese" as the fanboys claim. I don't believe the military in India would purchase the S-400 system, even for Delhi which has in place S-300 system difference being marginal at best in terms of actual performance deterrence difference.
India has Akash which covers 2000 sq KM which is a lot of coverage for a cheap SAM as cheap as AKASH and it actually has good all round capability against ground hugging targets like cruise missiles given its chase advantage.
Other thing is to not the eventual arrival of the LRSAM which is the Barak 8 with a longer booster. The biggest advantage to the S-300/400 long range missiles was that they could cover a large area like Russia which is for the most part flat.
India is in no way as big as Russia or as flat, so to have missile designed for Russian would be an expensive mistake.
India has Akash which covers 2000 sq KM which is a lot of coverage for a cheap SAM as cheap as AKASH and it actually has good all round capability against ground hugging targets like cruise missiles given its chase advantage.
Other thing is to not the eventual arrival of the LRSAM which is the Barak 8 with a longer booster. The biggest advantage to the S-300/400 long range missiles was that they could cover a large area like Russia which is for the most part flat.
India is in no way as big as Russia or as flat, so to have missile designed for Russian would be an expensive mistake.