It is not clear exactly what you are referring to when you say "plate condensers."  There are plate-in-shell heat exchangers that combine the advantages of a plate-and-frame unit with the pressure rating of a shell-and-tube unit.  These devices are welded plate pack inside a standard shell and can be used as condensers if properly designed.  Plate-and-frame units also can be used as condensers, however there is also a relatively recent design in which a semi-welded plate pack is used with an asymmetric channel pattern specifically for low pressure condensation.  This is referred to by the vendors as a plate condenser.