One major difference it seems between the Unicode and Ansi Drivers is 
that the Unicode Driver allows direct queries on the Postgres Tables 
while the Ansi Driver does not. The error that appears is Capability not 
Supported.

So I have been using the Unicode Driver for sometime and V12 of Postgres 
without any issues. Today though as part of getting everything totally 
sorted out for going forward I tried to go the Ansi Driver route as 
recommended.

It suits me to be able to directly adhoc query the Postgres databases 
for some things so I am going to stay with the Unicode Driver until it 
throws up some reason not to which will probably only be if we move away 
from mainly numeric data fields and types.