When doing research it is very easy to forget which tree you are on, your own or one that you are a member of but not the site creator.
It’s not uncommon to have several windows open to different sites to compare and copy information from another tree to my own.
Several times I have edited information only to find afterwards that I was editing the wrong site and that I changed someone elses tree by mistake.
The addition of a color banner at the top of the page to keep you informed of which tree you are on would go a long way to making sure people don’t edit the wrong tree by mistake. Instead of the generic Grey banner you have now why not make it green for the home tree and a different color for the sites of which I am just a member? Green for my own, yellow for member sites and grey for sites I am just investigating?
I would even be in favor of changing the background of the main page from white to a very light green and yellow to make it that much more obvious.