I do put the moisture absorbers into mine, not only because it's often humid here, but also because you just never know when/ where something is going to spring a leak. I also put a bay leaf in, because you'd be shocked at all the interesting things pantry moths can find their way into.
I do prefer drying slices, then grinding. I'm not the most graceful person, and I'm too concerned I'll spill a puree, plus slices give more options - they can be rehydrated and cooked in a gratin, a tart, soup, etc, and still have something to chew - and they can always be powdered, later, if you want to sneak some veggies into something. I also find thin slices dry faster than purees, because you're hitting more surface area, with the airflow. AND! Sliced stuff can also be eaten as chips. Just brush them with a little olive oil, sprinkle with salt &/or herbs, and pop into the
oven for a few minutes.