If the extra attack helps you win more against the types of empires you play it's worth it. But if your already winning most of your attacks I'd go with the crit% skill over the extra attack . In bosses extra critical% better also.
Could you maybe explain how you can get that much att with AK? It's Assassin seat so 900/2=450. The two Insignias might give 100 which leaves 350 to come from other sources. AK's rocket gives +2 for every street, there are roughly 40 street lts (according to wiki) and even if thats boosted by Yugo it won't be as high as 350. And even with the street insignia it would not reach a count of 350/2=175 lts.