How many times in your build with 4 Shows is Bargain better than Griselbrand? Especially game 1? In which matchups? When a sphere player puts revoker in and stones Bargain you still have a 7/7 Demon. If you've been aggroed down to a low life title they both suffer. Certainly below 8 is an important number.
Edit: Have you weighed the benefit of having 2-3 griselbrands as it relates to being able to side Oath of Druids?