Are you still experiencing battery drain with 8.06 update? My device still drops 3-5% a day when turned off or when in "sleep".
I'm also on 9.07 and have been decided to try Power Off (in the past, I have just let my Garmins go to sleep). After a full charge, I powered off and have checked every day for the past 10 days or so. Battery has been negligible (still shows 92% today). There is a big proviso here: I'm not 100% confident that the display is accurate because there have been problems with earlier firmware. Would be embarrassing leading a ride relying on a faulty display! To be fair, I haven't had any problems during the past 6-9 months (3-4 rides per week) so hopefully that's now sorted.