Re: Daito Ryu and Aikido
From observations of Daito Ryu (I haven't yet had to opportunity to train in it), I get the impression that DR places even greater emphasis on atemi: in a waza we would call "ikkyo" in Aikido, where we would have probably have one atemi, at most, DR might have four. DR seems to be more okay with practicing on the "edge of danger", but some strains of Aikido do as well (e.g. Birankai of the late T.K. Chiba-shihan; certain of his direct students, especially).
Aikido also seems to have dropped quite a few of the jūjutsu techniques of DR (as compared to the aiki no jutsu techniques), I haven't really progressed far enough in Aikido to express very well, in words, what the difference is between the two is, but the difference is there, none the less.
Finally, while Daito Ryu does seem to have a "sword that gives life" philosophy, it also seems to better recognize that there could be instances where it is indeed necessary to take life, as evidenced that much of their waza retains simulations of a finishing/killing move.