config best practice

[Egbert]

Hi! We will soon start upgrading our Ubuntu mail server (running 2.0.19)
from 12.04.1 LTSto 14.04 LTS.
The dovecot config is still pretty much in 1.x style; one flat file
called dovecot.conf. I can easily switch to a dovecot.conf with the
"!include" lines and rename my flat config file to local.conf. I've
tested that and it works fine. I could also try to move all lines in
local.conf to the different XX-.conf files in the conf.d subdir. What is
wise and best practice? Should one edit the files in conf.d? Or will the
files in conf.d be overwritten on an update of dovecot? Then I'll better
stick to the way of working with the dovecot.conf with the !includes and
local.conf and assume that all files in conf.d are default settings.

TNX for any advise!
Egbert Jan, HCC!hobbynet, NL