I would LOVE such a guild. And as to the above, I think the life expectancy of the followers would be dependant upon who and what types they were. The odds are that at least some of them would be powerful mages, in the tradition of Divyath Fyr and Morian Zenes, in which case, hostile cultists probably wouldn't worry them much. And only some of the Daedric cults are malevolent anyway. Azura's, Sanguines, Meridia's, and even Hermaeus Mora's and Sheogorath's seem to generally have a live and let live attitude. Unless you are a zombie. Meridia hates those.
But guys like Divyath Fyr wouldn′t let some lackey do the main research, at best they would tall me to... open up... and... swallow...*shudders at bad memories*
You are correct though that most Daedric Princes wouldn′t let the affairs of mortals bother them too much, but there are some like Nocturnal who would be anything but happy to have you "studying" them.