A good reason to do each on opposite sides. Almost never works out that the best reasons are on the same side. I love not having any debt and I wouldn't be worried about the interest rates and losing equity. If the real estate market and/or economy as a whole tumble, Fort Mill will only rise 6% instead of the 10-15% it's probably rising a year. Good problem to have.
For me it's the unknown of new neighbors. If you like your neighbors and house and can afford your current place, there is value in staying where you know you like the people who live next door. You have no idea who you are going to live next door to in the new location.
Likely this is what is driving your wife's desire to stay along with the usual nesting that comes with the holidays. I think this might have been a slightly better sell had you not asked right after she got done decorating the house for Christmas and company. I do agree this is an enviable position to be in. Well done sir!