VNC Firewall Solution - Packet Relay Servers

[John]

VNC Firewall Solution - Packet Relay Servers - where both VNC parties connect to a central server which connects the two.  Since both parties are using VNC Outbound connections (port 443) most corporate firewalls do indeed allow.  I know of EchoVNC (Scott Best's), EchoVNC (Echogent's), and CoPilot(3rd party service $$).

I'd like to learn more about this.   I support many clients who are behind various corporate firewalls and getting VNC (P2P) to work is usually tedious task.  A Packet Server could be exactly what I need.   I've been using TightVNC for years, all MS Windows environment. 


Questions:

1. Are there other products in addition to the above products I need to look at?  Any clear leaders?  Does the Packet Server really work?  Any serious negatives?   (Windows environment)

2. Since I prefer TightVNC (good file transfer), do any of the solutions support TightVNC client directly?   File Transfer too?    Maybe only need the TightVNC (viewer/winvc) on clients, no additional software, that would be ideal since many of my clients already have the TightVNC apps.