I'm giving Gnome 3 another try, and still find it very annoying to have to keep re-entering my password. (The machine I have it on is one of four on a KVM switch.)
I tried removing Gnome's own screensaver and installing xscreensaver, but that hasn't worked -- yet at least. (I've been too busy configuring this and another machine to find time yet for a log out and back in, much less a reboot.)
What I'm trying to eliminate is clearly not part of any screensaver, but merely a needless defense imposed by some other part of the OS.