NSE4 Certification doubts: 5.2 vs 5.4, Certification expiration, exam experiences

Hello everyone,

I will be taking NSE4 in the first months of 2017, and I have a couple doubts about it:

-Has anyone already taken 5.4 version exam? Any comments about it?

-Does it worth it taken 5.4 instead of 5.2 version?  Will 5.2 certification expire earlier than 5.4? Or they will both expire when version 6.0 comes out?

Comments and experiences from anyone who has already taken NSE4 will be appreciated.

Regards,

Gerardo