our first choice rep advised us only to go out during the day and that it was not safe after 6pm.
The reps often tell you that so you don't buy cheaper excursions elsewhere because they get commission on the trips they sell.
I have travelled many time to the north, south and east coast of the DR and have found it to be safer than a lot of areas in London. Even on my own, I am female in my 50's, I have never felt unsafe, as long as you follow basic common sense of not flaunting cameras, money and jewellery etc and stay in public places you are probably as safe there as at home. To make extra sure always carry your bag across your body or on the side away from the road after dark.
Lynn