Timely payments are one of the largest factors in a credit score and if he hasn't had late payments since then, his score would continuously improve.

The most major factor in most markets is affordability.

This may not seem like a big deal, but it is something that you will need to nail down and factor into your analysis.

is there a particular formula that takes all manner of factors, (employment growth, corporation development news, barrier to entry, rental rates, wage growth, etc) into account and spits out an "invest in city X" answer?

Factor in those costs (usually 8-10% of rent) when you're running your numbers.You mentioned the challenge of acting quickly on properties while managing your dental practice.

MAYBE they adjust that up or down 10% depending on outside factors but they’re not checking the assessed value. 

Its really going to come down to multiple factors, including your personal situation/strategy but it appears you are definitely thinking about things in exactly the right way.I'd say since it doesn't seem to be an "urgent" need - I'd advise talking to some lenders and since the rate environment is still moving quite a bit, settle on a interest rate / points combo that is "your number" and when market rates move down to that point - have the lender contact you and get ready to go, and just wait until that occurs

Good school districts make for better long-term investments, so it’s something to keep in mind when choosing a property.So while schools might not be your number one factor when flipping, they can definitely help increase the speed of sale and final profit.

Please work with an experienced lender to help you understand the right loan products.There is an operational cost to raising rents that does not seem factored into your process. 

Phil Wells, Peak Home Inspections, John Farmiloe, The Home Detectives, Steve Page, Integrity Property Inspections, PM me for email and phone numbers.