I honestly didn't think to talk about heat pipes when writing the report. Felt a bit bashful when I realized that a week after I turned it in.
So no, I haven't looked at how helpful heat pipes would be in energy recovery. They obviously aren't going to convert heat directly into energy, but I can see how they could be used to return heat to a reactor and raise operating temperature (either raising carnot efficiency or reducing required fuel intake, take your pick). Whether they can be used more efficinetly than thermoelectrics probably depends on the details of the reactor's design, but I'm not knowledgable enough to propose examples.
I would bet that heat pipes would need to be incorporated at a design level, whereas pelts can be stuck on to an existing process with little or no change to the setup.
edit: a quick googling gave me a good springboard link for heatpipe research.
clicky