You might be interested in Sideberry (1) - it has tab groups as an additional instrument of organizing tabs, and automatically creates daily snapshots of hierarchy of tabs.
I also us multi-account containers and would love to find a way to make the little ribbon of color on the edge more prominent.
I use a bit of userChrome.css for this. I think this is the important part:
.contextual-identity-marker {
width: 40px !important;
left: 0;
opacity: 0.6;
}