consult the dive operator at your destination for the local opinon regarding Mefloquine (Lariam).
I missed where anyone was talking specific meds, Are any doctors even prescribing Larium except in extreme cases? For Roatan I take Chloroquine which is cheap and to date have never had any issues. As far as making your informed decision, SERIOUSLY I would not be taking any medical advice from a dive shop owner or manager , there is a reason one must fill out a medical form when taking classes and not just ask the shop owner if its OK or not ..No, I will leave the medical things to the medical professionals.