I don't have any property in the DR (disclaimer) but it would seem that to summarize this thread;
1. As a buyer, if the owner is sitting on a property they haven't been able to move, it doesn't hurt to bring up the topic of owner-financing and at some low (or zero) percent rate. You never know how motivated someone is unless you bring it up.
2. For the seller, it's not going to be financially advantageous than an all-cash deal. Regardless of the rates in DOP or USD or type of investment (CD, equities, other real estate etc.) if the financing rate they offer the buyer is below what they could get elsewhere with the cash, they're loosing some potential gain. That number may be a little or a lot but again, to a seller sitting on something they want to get rid of, it may be worth it. Goes back to the 'never hurts to bring the topic up' conversation.
3. For the buyer, having the seller offer low/no-interest seller-financing will almost always be a financial "win". The operative word being financial since you will still have a 'relationship' with the seller long after the initial transaction is done which may/may not be off-putting. Each person has their own comfort level on this type of thing.
4. For both parties, watch out, do your homework and design a mechanism which provides protections against; (a) the buyer not getting the title after paying the seller in-full and (b) the seller getting stiffed by a deadbeat buyer who occupies the premises and then at some point stops paying. You're going to probably want a neutral 3rd party/escrow-type arrangement to handle how to address unforeseen issues if one side doesn't perform their obligations. And remember, you're going outside the traditional institutional (bank) arrangement of sale/financing/re-payment/title transfer so any protections that come with that arrangement probably won't exist. So being absolutely sure you're dealing with a reliable individual (if such a thing exists ;-) . We all know, dealing with 'personalities' in this world can be hard...