From what I understand, predator hunting involves calling, and waiting. I don't think the long barrel would be a big deal for that. One thing to consider is that depending on your barrel profile, the weight of the suppressor can cause a point of impact shift. As long as you were zero'd for the can to be on the rifle, it should work well. Suppressor effectiveness is very much a product of load, as well.
I think if you were shooting off of set of sticks or a bipod it would be fine, it would probably feel pretty heavy shooting it off hand.