upgrade from FC9 / PG8.3 to C7 / PG 9.6 - utf8

I'm performing a long overdue upgrade of a Fedora 9 / Postgresql 8.3 to a 
Centos 7 / Postgresql 9.6 system.

I'm just going though the config files to check that everything is okay and 
I've found a discrepency regarding language settings.  I realise things have 
progressed a lot since 2008 when I built this server, so I wonder what is the 
right thing to do moving forward.  The old system has

# These settings are initialized by initdb, but they can be changed.
lc_messages = 'en_GB'    # locale for system error message  strings
lc_monetary = 'en_GB'    # locale for monetary formatting
lc_numeric = 'en_GB'    # locale for number formatting
lc_time = 'en_GB'        # locale for time formatting

while the new system has

lc_messages = 'en_GB.UTF-8'    # locale for system error message strings
lc_monetary = 'en_GB.UTF-8'    # locale for monetary formatting
lc_numeric = 'en_GB.UTF-8'    # locale for number formatting
lc_time = 'en_GB.UTF-8'        # locale for time formatting

Am I best changing the new system to match the old one?
If I leave the settings as they are, enabling the utf-8, how will it affect
    a) the pg_dumpall / pg_recover process
    b) using the database moving forward?

Gary