Note if tenant has a credit score to ding, they have something to lose if I ding their credit.  

She, herself, has either flipped or built scores of houses.

My credit score is over 720, while my partner's is around 541 (on both Equifax and TransUnion), due to a collection that we've since paid.

This is incredibly helpful. 

Sure you will be required to maybe bring a higher downpayment and slightly higher rate.I can offer a worksheet if you provide:FICO score, DSCR ratio, state

One of our investor clients purchased a four unit there last year, and he has seen incredible rents 15-20% higher than initially projected. 

They are very more dependent on leverage and your credit score.

I'd agree with the above that the number is incredibly market dependant.

:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

Wow, incredible work.