Downsides are that he gets none of the potential upside when the property may be sold down the line, and we have to find a way to ensure that we build enough equity in the property to do a cash-out refinance when the loan term ends to pay it off. 

Some pay distributions, others don't, at least for the first year or two.

I am paying for the rehab with about $15,000 of my own $$ and about the same in credit cards.  

He's only warranting for two years.I wouldn't pay $40,000 to paint the entire interior and exterior!

If the septic is old and has several years left then maybe better to pay the connection fee - but if its in good working order - I would maybe pass on it as its available when the septic system is passed its life.

Pay in more frequent installments?

I assume the proceeds of the sale would go to pay back the tax certificate holder for back taxes, interest and court costs and then the overage would be split up by the heirs ?

Many flippable properties in my market are paying 75%-80%.

They are slow to respond, pay pennies on the dollar to low-qualified contractors, and often reject claims for things you thought was covered.

My PM failed to let me know about the 21 day itemized rule, let alone initiate conversation with the the tenants for repairs and those tenants are refusing to pay anything past $4100 due to that technicality.