I think 4 B-wings would be very tough to bring down. Focused fire from most squads would struggle to take down one a turn.
With the upcoming Hull Upgrade, you're getting the same attack power as 4 x-wings, a bit less maneuverability, and almost double the health. With the hull upgrades, I'm pretty sure its the most hit points you could have in a squad.
If you didn't want the extra hull, you could get fire control systems on all of them for the extra damage, or advance sensors for the extra flexibility.
Thoughts?