Hello Henk, I pulled the run time of a day,12hours on a primary CR123 at REDUCED OUTPUT, directly from the Peak sticky at the top of the Peak Forum page. I had heard that the output would be in the neighborhood of 400cp for the Rainier on a primary as opposed to 2000cp on the RCR123 battery configuration. As for output levels, Peak can get a little confusing by having lights that look alike but are of differing power levels. I believe that the reduced output is regulated although I am not certain of that or the quality of the regulation, ie:flat or semi regulated. Asking Curt or Robyn may be your best bet on tech information.
The Atlantic, Mediterranean, and the Rainier, all have the same body head configuration but each light is an actual power level/output difference so mine are all at stated power levels from the website. Peak could have just sold one light with three differing power levels in this style much like they do with the Baltic and the Pacific but as to why they didn't/don't is a mystery to me but being a Flashlight Geek, I don't mind surfing for the information. Their 5mm offerings come in different power levels as well but you may have the most up to date information because hopefully, they have sent you a CD of their "Current Offerings" of which I am sure that we would all like to see should you be able to post any information on the subject.
Check the Sticky at the top of the forum for a lot of details and then you can check your hopefully new information against what we already have here.
Have fun and I hope that this helps!