in the episode where Shinn took down the Gouf he goes into SEED mode after making his decision
well actually more during the making of the decision
to summarize it it went something like this: "long monologue from Athrun to Shinn" "Shinn doubts" "Athrun talks more" "Rey puts his foot between the door and interveines" "Shinn's forced to make a choice" "Athrun and Rey clash while they both are talking to Shinn" "Shinn makes his decision, goes SEED and takes down the Gouf"
and then afterwards he has some serious regret as can be seen
so stop making it sound like Shinn goes into SEED mode just to "escape" decisions, because that's how you make it sound
also the Shinn/Kira comparison about going SEED with the intent to kill, do you remember Kira from before the "final battle" with Athrun? when they were in Strike and Aegis? Kira went SEED with the intent to kill in that battle, and in battles before that he did as well