Ok, the use of them as Planetary defence seems nice. Real cowardice though on the pilots who have volounteered to fly them. At least the engineers see plenty of action, fighting mecha warriors and all that.
The advantage of the really fast streakers is that they can send the alpha strike quite quickly, and away from the fleet, then return, re-arm and re-Alpha under the cover of the fleet protection. Not to mention that they might be able to deliver their salvo from a quite short distance due to their size and speed (making them difficult to hit).
The 28 Streakers would have say 24 missiles carriers, and 3 spotters, deliver a load of 24 really fast size 6 missiles (since we can save on fuel in the missiles if we intend to send them much closer), wich we can assume might get through PD to a higher degree than slower missiles fired from further out. In comparison the FAC would deliver 160% larger salvoe, but from further away, and they have a larger risk of getting picked off during the engagement, prior to delivering their weapons. So both the weapons carrier, as well as the weapon itself would have a lower penetration toward the target. On top of that this is a more expensive weapons system, which takes longer to build, and cannot be built in normal factories.