What would be the benefits and the downsides?
Here's what I think, based on a source outside the elder scrolls.
1. Drinking daedra blood would burn you from the inside and cause horrible pain and most likely death
2. Drinking daedra blood would give you the ability to sense daedra
3. Drinking daedra blood would taint your body and leave a huge mark on your body. F.Ex blackened skin and daedra traits on looks. (Daedra worship)
Adding to the 3rd, a vampire wouldn't be able to hide his/hers affliction from people but they would most likely think the drinker a daedra of sorts and run while soiling themselves.
Just my reasoning.
Discussion?