Vaporeon is just an example of how weak BS lax is hitting.
BS curselax doesn't beats de curselax lol. Return/Frustration might with crits, but BS doesn't. What game are you playing?
DE forces rest loop, and all it has to play for is a speed tie. CH's will do like 80%. And 3 high rolls is enough too.
For BD lax, BS is better if you're a rester. Return/Frustration if you run LK.
Par nets you much more than that. You're neglecting the speed decrease altogether.