I think some people are missing the point about target control. If my opponent focus fires on Serrisu instead of my closer and still very fragile Kihraxz then I dictated the fight to them. Both the Kihraxz and Serrisu cost the same, and in fact I haven't lost anything more if they focus fire Serrisu, than if I lost a Kihiraxz with its bigger gun.
PS2 Kihraxz are reasonably likely to get PS killed and that is bad for a list that needs to throw a lot of dice to be effective. By encouraging my opponent to shoot Serrisu they are less likely to take the range 1 shot to kill a ship, even better they likely didn't shoot at the ship on the initial engagement and now it sits at full health rather than being damaged and thus more likely to be taken off the board before it shoots.
There are subtle advantages that go way beyond the rerolls on defence, and that is why Serrisu is a subtle Biggs.
On further thought I would likely go with 3 x Maurauder with Glitterstim, Serrisu, and a ZPirate with Feedback (likely) or Dead Man Switch (for a laugh).