Tbugs, FWIW - - -
I believe some folks just want to have new homes......probably for a variety of reasons. For example:
a.) You get to have some input/decisions regarding the details of what goes into a new home,
b.) You want to be in the area surrounding 466A (at present), and/or
c.) You simply want a brand-spankin' new home.
As with most transactions, emotions do come in to play. You want what you want for whatever the reasons, even if you could have done something perhaps a bit more financially favorable by going a different route - buying pre-owned, buying a smaller home, etc.
Re: the home-equity loan/HELOC to pay off the bond - I believe in many/most cases nowadays, those types of loans carry variable interest rates whereas the bond rates are fixed. Granted, you can probably get a lower initial rate with the new loan, but then you're rolling the dice with what might happen with the interest rates as time goes on. However, on the other hand - as you stated - the interest paid on the loan should be tax deductible - the interest you pay on the bond is not.
No perfect answer(s) for everyone!!
Bill