It's a gamble, unless you have some inside info.
A loan in the US will of course be in dollars. A loan in DR will of course be in pesos. If the exchange rate remains stable, the lower interest loan is better. If the dollar exchange rate climbs too much, then a loan in pesos will be better.
Never heart about less the 9% in DRI doubt a US bank will give you a mortgage on a property in the DR. Are you taking a first or second mortgage on a property in the US or a home equity loan? I believe interest rates in the DR are between 6-8% for a loan on real estate. The term on the loan might be shorter.
LTSteve
Generally interest rates in the US are very low compared to the DR. I do not know about any US banks that will loan money on a property in the DR. I have heard that Scotiabank will finance but I do not know about that for sure.
This is borderline nitpicking but Scotia Bank is Canadian.