>are there any drawbacks in using 9.6 client with 10.0 server?
imho: you have to re-check the new improvements[1] :
some examples:
* "Declarative table partitioning" ( as I know, you can't see all information from psql9.6 )
* "Stronger password authentication based on SCRAM-SHA-256" ( if the security is the first priority )
The method scram-sha-256performs SCRAM-SHA-256 authentication, as described in RFC 7677. It is a challenge-response scheme that prevents password sniffing on untrusted connections and supports storing passwords on the server in a cryptographically hashed form that is thought to be secure.
This is the most secure of the currently provided methods, but it is not supported by older client libraries.
* changes in sequences ( "a new pg_sequence system catalog" ; "The output of psql's \d command for a sequence has been redesigned, too." )
* changes in "psql" Client Application
Imre