IMHO the main problem with these NM is that you can fight them at rank 50.
I tryed to kill Unknown Soldier with a rank 35 full party and it was a damn taught fight *-*
The problem is that almost everyone in game has a class at rank 50 already, or knows someone with a rank 50 that can get the drop for him, so this isn't a challenge for not only for rank 50 people, but for everyone. Also, for a rank 35 party is impossible to camp them, cause they are overcamped by rank 50 parties, wich are way quicker >.> a party of the proper rank would take ages to kill one of them and it would cause the rage of all the other people camping that could kill one in 2 minutes.

Those NM could add a great content to the game if they were fought at the proper rank, IMHO the fights would be much more challenging than any Dodore or Great Buffalo fight. But honestly nobody wants to waste time if they can be killed in 2 minutes ^^'
They should add a restriction so if you have someone whose rank is too high for that NM you won't get the drop, also make them give a huge amount of SP if killed at the proper rank; this way we'll be obliged to fight them at the correct rank and even if we don't get the drop we won't feel like we are wasting time.