All pros! (Though I will admit to being a bit biased, since I'm from Maine). But seriously, Maine Sea Vegetables is a quality company. I haven't tried the kelp granules, but their dulse and laver are really good. As for iodine loss, I would expect that this would happen to iodized salt mostly because the iodine is added artificially. Seaweed would hold on to its iodine for a long time, I would imagine, because it is incorporated into the whole plant.
I would recommend switching up your seaweeds--have some dulse, hijiki, kelp, alaria--or wakame, nori. They all have different mineral & nutrient offerings. Fresh dulse is a treat on the Canadian border. It's soft and delicious when it's fresh.
I also recommend Maine Seaweed. It's just a guy named Larch and some summer helpers. He has bulk discounts.
Alaria (like wakame) $32.
A 3 lb family pack is $72.'
Not affiliated--just like their seaweed.