If a house is left unoccupied in the winter, is it better to winterize (ie drain the system) or use antifreeze in a closed loop hydronic system? 
Which is more convenient?   (ie draining/refilling water vs charging with antifreeze mix)
Does any potential advantage of antifreeze offset the added inefficiency?

Details:
Small house in Maine (25K BTU Heat Load), Average minimum low 14 degrees, Hydronic closed loop system, Mod/Cons boiler such as Laars Mascot HT330 (also used for DHW).  House isn't used Nov-March some years.  Note that the DHW system would be drained regardless.

If I used antifreeze I would probably use 30-40% Propylene Glycol mix and set up the system to maintain in house temperatures above 15 degrees.

I know the Hydronic system is slightly off topic for this forum but I think the expertise here is better :-)

Tom

Rob,

thanks for your reply.  For Belfast, ME, what ratio of Propylene to Water would you recommend?  Again, I'll have the system set up to cycle if the interior temp approaches the mixture freezing point.