I would be more concerned with getting out from under the PMI payment. I don’t think the average buyer would understand or even care about the assumable rate. You might be able to get a small premium at most. For the most part, buyers are using search engines at the max amount they can afford based on pre-qual. If your house is listed above max amount, they won’t even know that it exists. Also price is more important than rate. You can always refi if rates drop, but you can’t refi out of the inflated price. If rates go up above 6% or more, you might have something of value. You would also probably have to carry a second loan for this to work.