Hmnn, well, I call my primary teacher "sensei" out of the dojo too. He is Japanese, and maybe that is part of it; maybe it is partly as the norm from the dojo I was brought up in. I certainly address Yamada Sensei as Sensei, as well as Chiba Sensei, Kanai Sensei, and Shibata Sensei.
Folks who are more contemporary to me I generally call by their names outside the dojo (not in the dojo), but then again, they are hardly that senior.
The harder one for me is the sensei who are Western and in the 5th, 6th and 7th dan range and seem casual. My inclination is to call them sensei too, both in and outside of the dojo. Sometimes I get corrected and asked to call them by their given names, but I would prefer to err on the side of formality rather than be too casual.