40 bags before emptying the ash pan in the P43 is really good. To give you an idea, the ash pan in my P43 is full after < 20 bags of the GS Northeast Blend. Think you got a nice score with the GS Allegheny.
I'm pleasantly surprised with the heat level from these pellets. I typically run the stove on "2" on overnight (GC I-60) and it keeps the lower level around 70; main level around 63-64. Last night, I ran the stove at 3 and it was in the lower 20's overnight. Woke up to 78F downstairs, 70F upstairs. Thankfully, we leave the bedroom door shut so it was nice and cool in there.
Have you tried separating the dark ones from the light ones and burning them independently to see which are better?
Funny some lacretes I picked up recently are similar; lights and darks mixed in the same bag. Looks odd but they burn the same as usual.