I'm not too sure about those alternate items being brought up for SubBU Braviary. Even though it does have recovery in Roost, the 6% from Leftovers is very important when trying to keep Braviary's health as high as possible to prevent yourself from being forced to Roost too much. Leftovers is especially valuable in this Hail metagame to prevent Braviary from being worn down as fast by Stealth Rock and Hail. Sky Plate, Flying Gem, and Salac Berry really don't fit SubBU Braviary's playing style; why do you need a boosting item on a slow, bulky, set up Pokemon. The immediate power could come in handy in some situations, but you should just be boosting up with Bulk Up if you want the power. Salac Berry on SubBU falls under the same category that it just doesn't fit on a slow, bulky set. The standard 252 HP / 240 SpD / 16 Spe spread doesn't benefit much from the +1 Speed boost anyways, only hitting 300 Speed and the faster 80 Spe set still only hits 324 Speed. Any more Speed investment will just be making waste of Braviary's bulk, which is what SubBU should trying to abuse to the fullest.
Salac Berry could be interesting on a more offensive Bulk Up set and I might try something similar later. I was thinking something along the lines of:
Braviary @ Salac Berry
EVs: 252 Atk / 4 Def / 252 Spe
- Bulk Up
- Brave Bird
What I would hope this set is capable of doing when I test it is to offer a set capable of providing offensive presence, decent bulk, and sweeping potential all at the same time. I would spam Brave Bird and Superpower, heal with Roost when needed, and boost up with Bulk Up when given the chance. Once Braviary gets low enough to activate its Salac Berry it would hopefully have a Bulk Up or two to tear apart teams. Thanks to the defense boosts from BU and Roost it wouldn't have to worry about priority as much as other set up Pokemon (especially other Pinch berry abusers) once it's fully set up.