Right, 400 Mhz is more penetrable. Now, there are other factors such as antenna efficiency and how far away the satellites are. I think overall plb's are said to be more reliable. I think plb's can also triangulate (in 40 minutes) if they cannot receive a gps signal.
Ham radio is best as noted above.
GMRS is 5 Watts and you can put a high gain antenna on the unit. FRS is 0.5 Watts and you are restricted to the inefficient antenna the unit comes with.
GMRS is a better bet if not getting a Ham license.
