i wrote that a while back and i still agree with it. i just nuked another tank just to get rid of them, and coincidentally it was my yellow shrimp tank. i have been trapping the scuds from that tank to feed my dwarf puffers, chanoides bettas and chocolate gouramis for 6 months now. but even with removing 100+ a day, they still overan the tank (15g). there were only shrimps in there so no natural predators to keep them in check. last straw was when i caught them taking down another newly molted shrimp. breeding had gone down as the scud population went up, and i hadnt had any recent babies survive at all in a month. could be water conditions, but i dont think so. scuds only become an issue when there are no predators (fish) to keep them in check. i have them in all my planted tanks, and they are not a problem because of the fish. its only in my shrimp only tanks i need to make sure they dont get in.
with the plants you have, only the moss is really in danger, they will eat it to the stem in no time. i have found that they dont touch fissidens, so that may be another option instead of the moss if you cant erradicate them.
they infest pretty much any tank you come across here in Hawaii and many freshwater streams and lakes as well. the way i keep them out of a new tank is to rinse plants well under a good current of water, then put in a clean container for a few hours, rinse again, and repeat for a couple of days. rinsing removes the adults, but its the babies (so small you would barely notice them) that are harder to remove, and thus require multiple washes. it only takes a few to start an infestation all over again. just be patient and rinse well or do a bleach dip. good luck.