Sure there's much more to Aiki principles. I guess the question becomes, can a Judoka, Jujutsuka use Aiki principles in there Judo/Jujutsu? I think this is what Roy Dean has been trying to demonstrate in his approach to martials arts in general. Roy Dean knows Aikido, he is a 1st dan, but incoporates Aiki in his BJJ. I think he has a great approach to Aiki and self defense.
I use the principles all the time in BJJ and Judo. The challenge in implementing the principles is the difference in timing and the assumed parameters and rules, that is what messes you up when you are learning things. Once you can come to grips with these conditions/parameters, you can start exploring the prinicples of aiki in everything that you do.
Even in everyday life, from walking down the street, carrying boxes, lifting, opening doors...it is universal.