I think the line "I think you'll agree if one of us dies the other will too" goes more towards the Master/Doctor like thing than the Davros/Doctor because The Master and The Doctor are both timelords, the last of the timelords, and it would mean the end of a species, I.E "The other will too"
I think the line "I think you'll agree if one of us dies the other will too" goes more towards the Master/Doctor like thing than the Davros/Doctor because The Master and The Doctor are both timelords, the last of the timelords, and it would mean the end of a species, I.E "The other will too"