As per previous post upgrading from GW7SP3HP1 to GW8. The installation
routine for the agents has a check box for "Install the software files, but
do not configure the agents". It's suggested in the upgrade guide to check
this as you don't need to change anything with existing agents, however
there is mention that the MTA startup file has a new switch "soapport" that
you need to add if you have more than one MTA on a server (which I have 2
servers that meet this).

In the past when doing GW upgrades there was no such option and you provided
your domain and post office info, let it create the startup files, and then
(in my case) did a compare between the new and old files and made any
adjustments. I'm thinking I'm going to continue this way, it's not really
that much work, but like this my startup files would always have any new or
changed switches available (or I'd notice a new one being made available and
check to see what it does). Does anyone see a problem with this approach?

Same idea as the GWIA install recommendations in the past, don't use
/COPYONLY as you wouldn't get the new GWIA.CFG entries...