But this I do know:  every single AVM I have tried from Zillow and other is way off on my own personal residence by a big margin.

I didn't actually know someone came up with a name for it until after I'd closed my first wholetail deal because I couldn't find a single person in the entire company that had actually done it.

I just did a single family residence deal there earlier this year but it was a 1 unit so loan limits are 554,300 as opposed to yours which is $709,600 so it looks like your loan amount is below that which may help you get financing if you're considering a refinance.FHA allows a cash out to 85% of current market value so if you believe you're at 603,000 loan amount then you'd need a min appraisal of 709k or so to refinance this home into a conventional loan if you're trying to remove mortgage insurance.There are lines of credit to 89.90% or 90% of your homes value if you're interested in having access to your equity (if the property appraises high enough).To address your questions:1) If it appraises high enough yes you can remove monthly MI and you can use a line of credit 2nd to access your equity (this would be your best bet).

Would it be better to purchase multi family property or  (1 - 4 units) .... single family property or does it matter ?

Once renovated they are more attractive as buy and hold investments, but they also can be partitioned into two single family homes, which have higher comparable sales in these locations.

I have been a single family investor mainly. 

Yes, you will have a higher interest rate but you have to look at what it is going to cost you: If the higher rate is going to cost you an extra, say, $30/mo and your closing costs are, say, $6k, you are betting that you are going to keep that loan for over sixteen years. $6k/$30=200 then 200/12=16.66(yrs).  

Vetted the prospect thoroughly and thought it a sure bet.

Hi @William McLeodIf you have any questions on turnkey single family rental investing in the Metro Detroit area just let me know.

That would be your best bet.