If you got on the 6% bandwagon lately, there's no reason not to take out a 30 year mortgage. If you were staring at a 19% mortgage in 1979 or whatever, then yeah.
until the value of your house crashes
major price corrections are coming. i've been pouring over data this week. it's going to be impressive!
edit - where i live, i wont be able to afford even a 1br condo until i'm making 80k and there's another 5-7% price correction. 10% would be amazing. it's cheaper to rent