Seller insisting rent to own, unsure of process

[David Domine]

Found a profitable hold property but the seller is insisting on a rent to own contract. Short story is the seller bought the house from wholesaler, used a 82k private money loan(11/16) from a local investor with 1 year minimum interest, 3 year balloon. The seller and I have agreed on a sale price and I asked to assume the loan. The seller won't allow me to assume the loan and is insisting we do a rent to own contract with 10k down,and he continue to cover the taxes and insurance. I've never done a rent to own contract before so am not familiar or comfortable with the agreement he has proposed. 

My question is if this is a safe/secure method of transaction and if not why, if yes what steps do I need to follow to cma with title, liens past and future, and ability to finance out in 6-12 months? Thank you in advance for your advice.