This ship is too expensive at 400. I must've missed something in the old BFG:R. The last I knew it was 390 with the option to replace all its prow launch bays with a strength 9 torp salvo at no cost (yes, an underpowered option). Now it's 400 (overpriced) and you can replace 2AC (6WBe) with 9 torpedoes (13.5WBe) for no cost. What? Why wouldn't you do that all the time?
I get that AC is valuable and costs more than it's WBe due to its defensive nature, but that's a biiiig gain for no cost. Drop the base ship back down to 390 and give the torp upgrade a 10 pt price tag. At 390 it's already at the high point of its acceptable price range.
Edit: Ok, so the torpedo trade does change the role of the Despoiler from stand-off support ship to an attack carrier for which it's not all that well suited, but it's still a fairly significant gain. Anyway, the base ship shouldn't be 400. The extra firepower and speed compared to the Emperor isn't quite worth the points, Ld and turrets difference at 390 pts.