I did an owner finance when I bought my place last year. I also agreed to the former owners' terms of payments, which was not bad at all for me. I did double up on my monthly payments just so I could get it over with.
I would not give 90% of my money for a house as a down payment unless I have twice the amount in my checking/savings/retirement accounts knowing that I would be alright in the long run.
I say put 20 to 30% down as payment and then make the monthly payments on time.