I will try to answer your as complete as I can, but its been quite some time since PS60 have been discontinued by Pharos. The PS60 were great for allowing for a quick card authentication mechanism for single function print devices. The PS200 greatly expands on this capability however. (Quick note on PS150: These units were quite similar in functionality to the PS200, but like the PS60 they too have been discontinued and replaced by the PS200 units).
PS200 supports not only card swipe authentication but can be integrated to allow users to authenticate with Active Directory credentials via the touch screen. The PS200 can support Multi-function print devices so you can authentication, charge and track copy jobs as well as print jobs (Copy function support will require an additional cable for the Foreign Device Interface of the particular unit). The PS200 do not have to be installed inline with the print device ,so in practical terms you could position the unit anywhere in the same room as the print device if the need calls for it. However, when installed inline with the device the PS200 can act as a firewall appliance for the print device as well.
I'm not entirely sure what you mean by 'support 1GB network traffic', but if you mean can the PS200 sit on a Gig switch port then the answer would be Yes. This should not present any problems. Also from a single unit you could administer your fleet of PS200 units.
This isn't necessarily an exhaustive list of differences between the PS60 and PS200 but hopefully it give you an appreciation of the superiority of the PS200 over the PS60.
If you would like to discuss further and, perhaps see a demonstration of the functionality of the unit please don't hesitate to reach out to your Pharos Account Manager and we will be happy to arrange it for you.
Pharos Systems International