I have a policy with HDI through MexAdventure but I don't have a local sale rep through whom I originated the policy. If I had it to do over again I would go the route of the local rep who hooks you up with the insurance agency. That way you have a local contact who will do everything in their power to take care of your needs.
This is the local agent I recommend, Julieta Morales Vera. This is her website. She gives excellent customer service, she is bilingual and she has a good reputation among the expats I have talked to. If/When I renew my policy I will start it over and use her. You need a good local rep on the ground who knows the city. For that I recommend Julieta. Here is her email and contact info:
US.phone: (786) 342-0569
Telcel: 9991 63 35 61
Iusacel: 9999 49 31 32
Seguros Mérida - Oficina
Calle 72A No. 489 x 17 Col. Garcia Gineres
C.P. 97070 Mérida, Yucatán, México
Oficina: (999) 285 72 82
I would highly recommend that you pay a few dollars more for full coverage. Contact her and she can explain the details. This is one of the areas that you definitely want to get right when living abroad.