I believe that
No Weapon Drop on Death could be potentially unstable sometimes. While i widely tested it i couldn't notice that but one of the users reported so. From what i can tell is that it's not recommended to delete weapons with RemoveEntity or by FL_KILLME flag set methods because a weapon is represented as an entity pair and the both weaponbox and weapon_* entity is linked to each other internally by the Game, so breaking this "link" by entities deleting/killing may potentially lead to some unexpected results since some Game internal data structures haven't updated properly.
That's why i always recommend to everyone to use so called "natural" (Game default) weapon deletion way.