Advance refundings may be an appropriate target for the semi-jocund question, "sure it works in practice... but does it work in theory?"  A recent study of approximately 150,000 transactions which concluded that advance refundings "destroy value" is reviewed and critiqued in the following commentary featured in The Bond Buyer.

http://www.bondbuyer.com/issues/122_155/commentary-valuing-advance-refundings-1054558-1.html