For a meatier response:
My experiences with the Sabbat on MUs have been less than ideal. People usually use the rabble of the Sabbat as a template for all characters in it, and usually the structure of the Sabbat itself isn't enforced by the game enough for the themes of the Sect to really shine. When all people do in the Sabbat is RP Black Spiral Dancers But Vampires, I think it undermines the potential of it.
However, one of the best themes of the Sabbat, in my opinion, are the paranoia/conspiracies and its hypocrisy. Paranoia because you shouldn't ever be able to say for SURE you are not playing the games of the Antediluvians/Elders, and hypocrisy because, while the rabble is composed of drooling edgelords who like to Potence hard, the elite of the Sabbat is said to be just as callous and cunning as the Camarilla, making the movers and shakers of the Sect as dominant and manipulative as the elders they deem to hate for that very reason.
When I envision a Sabbat game, I envision a game where staff enforces the roles of the 'Sabbat Elite' through NPCs, information and plots (and of course allowing players among them), while keeping the rabble following their design. You want to play a mindless monster Pander of no direction but 'who am i killing now'? Sure, but that person isn't going to make Inquisitor, or the head of one of the Clans/Bloodlines, or even make it high in the Black Hand.
On the Sabbat vs Demon front, all I have to add is that the Sabbat works as a group, and stories can be about a Bloodline, Clan, the Sect as a whole, or even the Sect against itself (with Infernalism, etc). Players are all moving together in the story, which helps a community grow. Demon is a game about personal stories, and monumental shifts in the world that are supposed to be driven by characters. I find it weird to turn that into a cohesive game, and I would find it hard to find a reason to meet too many Demons if I played there.
One thing is certain: I think a Sabbat game could be immense fun, but it needs a strong theme and it will have to fight against prejudice from new and old players, as well as need to enforce its theme so everyone is either on board with it, or re-educated in what you expect of them in YOUR game.