When buying a house for a price that is higher than the current assessed tax value would the city always raise the taxes up to match the new purchase price?

You'll never be able to match the return with buy-and-holds unless you leverage (i.e, get a mortgage).

I'm not sure if an income approach would work for this property or not, but most appraisers would be interested in seeing it to see how closely it matches with the sales comps.

I have found that the reason I am able to get properties that match the 75% criteria is due to the marketing.

Tell that manager what you are looking for and ask her to give you 3-5 agents names that match your criteria.  

The downside, and you already said it, is that there is much less liquidity in that the market you're selling to is limited.It's crazy how similar a situation I have on my end though:The property behind my duplex is a matching duplex and was put up for sale with a residential realtor at $180k and pulling $775/side.  

We would definitely prefer to have the typical 30-year (or 20 or other longer-dated term) mortgage so that we can match our rental income against our mortgage loan payments (and also not have to pay a large, out-of-pocket balloon payment at the end of the 5th year).

Have you looked at just getting matching tiles to fix just the affected areas? 

I believe that the acquisition of the new Soccer team is perfect for Atlanta and will open up unimaginable opportunities for buy and hold.

Most offer a certain quality of data at a price point to match the quality and data coverage.