I bought some to try out, a quick comparison
left : figure on a base cut from clear plastic packaging (thinner)
centre: figure on Terra-Base, a bit thicker but Ok.
right: figure on terrained base - clashes with stone surface.
One risk of clear bases is the 'reflection' effect, this depends on lighting and angle of viewing; more likely with larger bases, as shown here with a 54mm figure.
I'm most likely to use them for my 54mm roman civilians. I'll stick to my scheme (bases cut from clear plastic packaging) for my 18C palace civilians.