Just my personal experience regarding this.
I tried to use Jitsi for past several months (maybe even a year) on GNOME
but while it does look the most promising VoIP client out there it was very
buggy for me (using testing, with sometimes bits from unstable and experimental).
Buggy - if I choose to exit app but not quit it (running in background) I can not get
it back (gnome-shell shows that there is that app but its invisible), sometimes
some part of menu get lost or get a top of each other (all this actually happens
almost at every jitsi run), never had a video conference with it (with another jitsi user)
and I do not recommend it for small systems because it eats a lot of memory (just
to run it its about 250mb of RAM). On the other hand I tried used Empathy in past
(GNOME 2 etc) but never got video conference/chat working but I installed it last
month and must say I had no problem - beside it greatly integrates with gnome-shell
it was matter of minutes to set it and video conference was done out of box (with
telepathy user from KDE desktop). So maybe Empathy should be default but also
JitMeet (as I hear from lot of people) could be included in default.