The only downfall to having everything T'd into the same vac source is that if it develops a leak or a hose blows, you lose everything, including the wastegate's ability to regulate boost, then boom.

Wastegate and BOV should each have their own source of vac, but it isn't always a perfect world.

How close does that crossover setup come to the TB or are you going to be going with a F-body or stattama passenger style tb setup?