Well hello Natch, long time no see!
You are correct, the first reason for the rotation is blend type. Also that they have had a busy summer and it seems time to let them rest. No need to abuse good smokers.
The winter pipes tend to have longer stems, as my facial hair can get a little wild and I'm disinclined to catch my face on fire. That and I get to sit a bit more often, so I can hold my pipes and relax. Also, I tend toward aromatics this time of year, and long stems allow cooler smokes while I'm freight training and staring off into the abyss.......
I will post a picture of my next rotation when I get home to a PC.
Good to hear from you sir!