Two other factors I try to keep in mind, but don't know how to quantify, are the dislocation of muni prices due to the credit freeze and the pending  Supreme Court decision.

 Lots of munis were dumped on the Market over Dec-Jan as hedge funds had to raise cash in a hurry, creating some real bargains.  To the degree that this is over and done with, price increases to normal may be a one shot affair.

The SC seems to be taking an inordinately long time to decide Kentucky v Davis, suggesting that they may tinker with related issues, such as private use and auction rate munis, even if they retain the status quo on the main issue.  This could impact both individual munis and the funds that hold them, particularly CEF where retail investor sentiment plays an outsize role.

 I find I can buy LSBRX without fees through my broker, so plan to switch some MGF to Dan.  Thanks for the tip!