I climbed Pico Duarte during the height of the rainy season, because that was the only opportunity I had to go (and it was something I just
had to do!) It really depends on your comfort and experience level with hiking. The hike is tough, I won't lie to you. If you are inexperienced with hiking big mountains, you can easily hire a guide and mules to haul your stuff, if that's your thing. They say January is the best time, weather-wise, but then you'll find hundreds of other people up there too(yuck).
When we got to the second basecamp, where we camped at ~8,000ft, it was hailing(
big ice balls) with thunder and lightning. I thought it was incredible, seeing the mountain light up and the winds rage, but I have been told that I am a little crazy.

The storms (yes, that is plural) were brief, however, and in the clear evenings you will think somebody upped the wattage on the stars, they are so bright!
All I can say, from my
limited experience there, is that
if you are prepared for the weather, you will have a great time. In my opinion, Jarabacoa and the surrounding mountain regions are tops.
buena suerte!