If I upgrade to 12.7 from 12.5, will the process encompass converting my existing PostGre database to a MS SQL database? That process is a goal of mine and this would be handy for sure.
No the upgrade will not auto convert to MSSQL for you. It is possible to change but you probably want to do a ticket and may not want to use an RC version to get that rolling. I would recommend a support ticket.