Ubuntu Studio default file manager?
 

In Ubuntu 12.04 the default file manager looks decent, what is it called?

Would Dolphin or Nautilus be worth a try? And can I go back to default later?

If you go "Help," "About," the file browser will tell you what it is. I think I read somewhere that Ubuntu Studio switched to Xfce desktop? If true, that means the deault is probably Thunar.

Dolphin and Nautilus are tightly integrated with the KDE and Gnome desktop environments respectively, so I would not install them unless you are actually using that desktop environment.