Evaluating a Nashville Rental, Calculating ROI, Sell vs Keep ?

[Ralph Noyes]

Currently have a 2bd 1ba 672sq ft SFH in east Nashville close to downtown, tenant paying $1245/month. (Probably a little under what we could've gotten in rent but we wanted to get it occupied before Winter hit last year...I suspect we could bump it to $1300 without scaring the tenant away). PM is managing it as we live in St. Louis. Got the house for 125k in 2014 on a 30yr mortgage at 4.375%, put 25k down. Currently owe 84k on the mortgage and the property is conservatively worth 220k - i.e. we've got about 135k equity tied up in it. After paying the PITI of $680, the 10% to the PM, and setting aside something for vacancy, maintenance, and Cap Ex it's likely only cash flowing 150ish per month.

What are your thoughts on this as a long-term rental? I'm thinking we sell while we're in capital gains tax free window, harvest the equity, and redistribute into the St. Louis market - either as a house hack or 1-2 rental properties. I know that over the long-term Nashville (particularly the area it's in) will likely appreciate well, but I think that equity will provide a better return in St. Louis, even if we just get some SFH's, but especially if we get into some small MFH's. 

As an aside...: When you're evaluating a rental that you currently own, i..e trying to calculate the Cash on Cash return, do you use the numbers from the time of purchase? Or use the current value? I realize that $1245/mo rent and 220k value is nowhere near the 1% rule...