thanks for that kevin. In our academy how we start off a roll isn't formal, it depends on body type, flexibility, preferece etc. I should have been more clear, I'm experimenting with starting rolls off using this sitting type of posture and movement
http://www.youtube.com/watch?v=6uVEZo-09jw
to set up bjj techniques. I was looking for tips and principles on this sitting posture from aikido practitioners who use it.