I've never tried Deca, but after hearing so many horror stories of hard and long HPTA shutdown, I don't think I'll ever touch it.
I think you have a solid cycle as it is. Adding EQ will probably boost your appetite and give you some vascularity, which are both pluses.
The gains on EQ are not bad at all. Since you already have Sust and Dbol, you're already probably put on a decent amount of mass with some bloat. I doubt Deca will add much more keepable size, especially since you're going to be shutdown so long after the cycle.