On my first try on the suicide mission almost everyone died. For some reason I had completely missed upgrading the ship. The ending was horribly depressing and I had to give it another try. So after I finished it I loaded it up again, bought everything I could and everyone survived. I'm glad I did that because playing through ME3 with 5-6 characters missing would suck. If I had had one character die or maybe two I would have probably moved on though.