Okay, let me say this is not my area, this is more a question, but am i correct in the following?

You need an additional 11k in equity to get rid of the pmi? By putting 5k toward the principal along with your tax return of 4 k and a few additional payments to bring that figure up to a total of 11k, you can save about 1.2 k a year for 4 or 5 years? I get that the math is not nearly as simple as that since we also have to compare the investment return on thr Roth invested money which is certainly going to be higher than the interest saved on the mortgage, and then of course the tax savings down the road, but those figures don't seem like a slam dunk for the Roth to me. There is also additional money in the extra 1,2k a year that could be invested.