[RadioKid]

Let me explain what the listener think when each replies are made.

Scenario 1
いいよ　(ii yo) - Fine. : why he is so friendly?
いいだろう。　Fine. : He is not afraid of me
大丈夫　(daijoubu) Okay. ??? Does he agree with me or not?
はい　　(hai) Yes. : He is soooo tame.
するよ！　(suru yo) I'll do it! Why he is so happy?
(I think usually Japanese will say nothing in this case)

Scenario 2
いいよ　(ii yo) - Fine. : He is a good guy.
いいだろう。　Fine. : He is so arrogant
大丈夫　(daijoubu) Okay. Does he agree with me? or ignore me? I must ask again.
はい　　(hai) Yes. : He is too tame.
するよ！　(suru yo) I'll do it! : OK, he is happy t do it.
今回だけな （KON'KAI DAKE NA：Only This time(never do it again)) : hmmm.