I use ultravnc SC because i help blind people and SC is really easy to use for them. (just need to launch the SC)
But SC have missing feature :
-Don't capture alpha (really hard to help when an alpha box is shown on client screen, because niether me nor the client can see the box
-Very slow screen refresh since poll screen is disable
-Some UAC problems (when UAC is require, i can't use the elevated program)
But SC is easy to use for us because there's no need of a repeater, no installation (except for viewer side, easier for me), no nat configuration (except for me, but, there's no problem with that)
So i wonder if, and how i can replace SC with ChunkVNC.