A humbly submitted perspective on VNC
Have you checked out TightVNC? It's gpl'ed and does most everything the pay versions do including file transfers. About the only thing it lacks which apps like RAdmin have is remote install in a domain environment. It's nice to be able to push it out to 30 workstations from a management console.
I'll probably get slammed for this, but it needs to be said.
VNC is open source, and I LOVE open source. I love how passionate the user base is. I love that the "products" are "free". I love the independence and the feeling of sticking it to the man.
It all gives me a vigorous sensation similar to the one I get reading
Henry David Thoreau's Walden or Self-Reliance.
Use open source and clear your cookies!
That said, there some compelling reasons NOT to use VNC, and pay for a product instead.
First [and of debatable importance] VNC can be more time consuming to use than a purchased product.
To quote Thoreau, "The cost of a thing is the amount of what I call life which is required to be exchanged for it, immediately or in the long run."
Secondly, and of profound importance, is security. When you're connecting to customer's computers, you need a solution that
-logs and records everything that has been done on that computer
-makes no changes to their firewall configuration
-makes it incredibly easy for the user to regain control
-offers multiple levels of acceptance/authentication before control happens
-leaves no residual software on the remote computer
There's a ton of other
security issues surrounding remote desktop support (a list www.bomgar.com) that one should take into account when choosing a solution that does something as touchy as controlling someone's computer. The base code of VNC is simply lacking many of these security measures.
Original versions of our products when we were NetworkStreaming used VNC as part of the architecture. We left the VNC base, rewriting our code from the ground up with version 8 [i think. Our release log is here
http://www.bomgar.com/blog/tag/new-features.] Among our many reasons for leaving VNC were its inherent security issues.
These guys made a similar decision http://www.tridiavnc.com/.
In summary, I'm not anti-VNC. There are a number of setting in which VNC is probably a fine product to use. However, in implementations where security is a prominent issue, the use of VNC should be heavily considered.