So it looks to me like, if I want to go with Stable sources, for the long run I need to drop that Minto repo. I'm thinking that if I just install a Xfce4 desktop onto my Mate/Cinnamon LMDE and run Stable sources it should be fine. Without the Mint repo I'd have to manually install and update Firefox and Thunderbird, or just use Iceweasel & Icedove. It looks like I can directly install some apps from the web, if they don't conflict or cause dependency problems.
Here is my concern with Testing and security: http://secure-testing-master.debian.net/ It does not get security updates as soon as Stable, and sometimes not at all as it is waiting for patches from Sid. So if you stick Latest in the mix where updates are even later in coming...and you see one of my concerns with Testing/Latest.
My take on it then is that LMDE offers an excellent out of the box snapshot/system that works up front very well, but to keep it like that you either put a self-imposed freeze and don't update anything, just use it until it becomes unusable and replace it, or stick to Latest repos, which offers updates few and far apart, and no guarantee the updates will not bork your install (though Latest will be a safer bet than pointing directly to Testing). Or do as I likely will and set the repos to the New Stable when it arrives, get more rapid security updates but be responsible for updating the apps yourself.
This is a hard choice for someone who doesn't just want to play around and experiment with their system, but actually wants a reliable, dependable LMDE.
Much food for thought

Thanks.
kbd47