I read that the proprioceptive stabilizing effect of having your upper body in control with hiking sticks means that the knees need to work 10% less hard. On a 20 mile day that may be the equivalent of saving 2 miles of work.
Hiking sticks aren't proprioceptive, they are a substitute for proprioceptive stabilization. Trained balance weighs less and is still available after you have set up your ultralight tent.
The UIAA MedCom suggests them for the old, fat, ill, and over packed and not as a full time practice for others:
http://www.theuiaa.org/upload_area/files/1/UIAA_MedCom_Rec_No_11_Hiking_sticks_2008_V1-2.pdfDale B. Dalrymple
