Just a heads up this will not be tax free, it will be a pro-rated exclusion.

Depending on how risk adverse you are, going out of state can make sense, but I always recommend investing in your backyard (or at least being driving distance). 

The increased cash flow would make such a substantial difference in your daily life that not paying it off would be foolish.Outside of that, I can't see many reasons I would take a 15% tax hit to save 4% on a mortgage, which is really only effectively about 3-3.5% depending on your tax bracket.

Here's a bit more in detail about how rates are calculated for DSCR loans:1.

Expenses went down and ratings / reviews went up.I did the switch after staying in an Airbnb that provided both flowers and local bakery goodies.

I don't know that any of this would affect a new appraisal, but there may be some comments by the appraiser, which may or may not hurt you depending on why you want the appraisal in the first place. 

If it was due to a natural disaster they cannot raise your rates.

But SFH are already seeing renewals at 2%-4% and release rates up at least 5% YoY...that number is even higher on some luxury ($3k+/m rent) homes as those are harder to find.The rest is entirely speculative.

The best amenities for Airbnb in terms of ROI often depend on your target audience and the location of your property.

I would find a loan officer that does both conventional and FHA renovation loans to compare which has better rates and terms for your situation.