Is there an extension that would allow me to choose Firefox profiles that contain different extensions and/or themes before startup (but using the same version of Firefox)
I'm actually looking for an extension... I would like to run a barebones Firefox, a testing Firefox (a couple of addons), a loaded Firefox, and maybe Firefox with different themes. (Is this part of what different profile does?) And I would like to select which profile I would like when Firefox starts (and when I want to change my option I just restart Firefox)
I don't think that you can do it as you want (restart Firefox with a different profile).
You will have to close Firefox and use the Profile Manager to choose another profile.