POF is the same thing as a Pre-Approval letter.

They can be tough to close. 0% intro APR credit cards is another slightly riskier way to accomplish this

For my wife and I, syndications were the BEST way to go.I had a wake up call during a snow skiing trip.

Besides, all you need is one bank to create a pre-approval for your offer. 

You could use a zero APR credit card for 18 months, you could use an unsecured loan, you could do just about anything and come out financially ahead as opposed to paying an extra 1.5% on a 200k balance for no reason. 

I agree with your points and should have added some additional detail in that although the loan would be amortized over 30 years, we would include a balloon payment (to give me the option to refi) and a pre-payment penalty (to give the seller assurance he'd continue to accrue interest for a guaranteed period of time).  

Any thoughts on the ski hill or mountain biking and sledding ?

We are using seller financing for the loan for 15 years with 2.00 % APR and I’m covering all the attorney fees.

I used standard financing that would be available to me as a new investor in the calculation, i.e. conventional 30-year fixed mortgage, 20% down, 4% APR, although even this may be overly rosy. 

I talked to my usual bank (Chase) and they said 4.3% APR and 25% down.