Ok, let me explain it in other words:

You've got it - but I'd like to have an option for the tab's title, because having "Fast Dial (Work)" or "Fast Dial (Home)" (both are the exact names of both folders) isn't really what I'd like to have - instead, having only "Fast Dial" or even a customizable title like "Firefox :: Home" would be much greater.. ;)

With regard to the sub-folder support, I assume everything is understandable? :)

@martin b

You've got it - but I'd like to have an option for the tab's title, because having "Fast Dial (Work)" or "Fast Dial (Home)" (both are the exact names of both folders) isn't really what I'd like to have - instead, having only "Fast Dial" or even a customizable title like "Firefox :: Home" would be much greater.. ;)

Why don't you just rename these folders to the names you like?
Fast Dial remembers home folder id, not its name.

If you go to Bookmarks/Organise Bookmarks and select the Folder that you wish to rename, you can rename it what you want there.

My Fast Dial Root folder I simply call Root, which I prefer to see in the Tab to the name Fast Dial.
Works fine

Of course Foxmarks is sensitive to the Folder name.

Many thanks

Well, the problem with your suggestion(s) is that I can't have two folders with the same name - from my point of view, having the tab called "Fast Dial" on both systems would be fine, but that's not possible.. Foxmarks would merge home- and work-bookmarks into _one_ "Fast Dial"-folder..

Sure I understand
This possibility was created in Fast Dial for Foxmarks users

Rename your "Fast Dial" Folder on either machine to whatever name you want in Organise Boomarks
Once in Organise Bookmarks go to Bookmarks Menu

Select the name of the Folder Fast Dial
It will appear at the bottom of screen under Name.
Change the Name
Hit Enter
Hit close (top right)
Restart Firefox
Fast Dial Folder should be renamed.
You should see the effect immediately in the Tab name when Fast Dial first opens, as the Root Folder name should appear in the Tab