One interesting question i think is the nature of their deployment.
Assuming Catsoo is correct in this case, and their range is 50+ km (which is roughly in line with other SDV's of the same size) and they use GPS to navigate (which is reasonable to assume), they would still largely be restricted to operating from a few limited locations, notably the Islands in the Persian Gulf.
However, given Iran's close cooperation with North Korea on all types of weapons development, a logical development would be to deploy them from mother-ships such as a disguised dhow or trawler, such as how Iran mined the gulf during the Iran-Iraq war.
Looking at the picture of the Taedong, it looks like it could carry twin 324 mm torpedoes, but i cant say for sure, those could be storage cylinders.