There are only 2 risks I can think about.
1. The buyer is not going to come up with 20-25% down.
2. Bank may decide to exercise "due on sale" clause.
For risk #1, would you rather let the house sitting there, hard to sell, and paying property tax, insurance, HOA fee or take very minimium down payment, even 0 down to have someone move in and make a regular monthly payment to you?
To me, let it sit there without any income is riskier.
For risk #2, I can assure you that you have less than 2% chance your loan will be called, statistically. There is nothing gurenteed in investment. If your odd is 98 against 2, what are you worrying about?
I see constently people taking unfavorable odds in stock invenstment. When has 98 agianst 2 suddenly become a high risk event? I don't get it.
For people in areas with high median house price, this is practically the only way to make it work.
I personally did wrap around mortgage, also did seller finance on 2nd lien on a commercial property. Every one thought I was crazy to carry a 2nd lien on a commercial property, it is not as bad as it sounds. In commercial deals, everything is negociable, therefore thinking out of box is very important.