Some of your points are valid (e.g. savings earning rate likely to go up), but for the here and now, you’d be losing money *and* you’d need considerable income to cover the higher payments (or I forgot, are you liquid or not?!).
My calculation shows that the saving interest you make should cover most of the difference in the increase mortgage payment. If my calculation is wrong, please show me. I’m hear to learn just like everyone else.

And whoa, I don’t even get what you’re talking about regarding prolonging the tax write-off (and I suspect you don’t either). Finally, compound interest, taking advantage? How do you think a mortgage works? I think it might be taking advantage of you…

All I mean by this is if the difference in savings rate and mortgage rate gives you an advantage, why not extract your equity and have it work for you with no extra risk? You can always pay it back anytime.