I just did one (Operation: Kobold as Ice) as a r18 Marauder. I went in a little apprehensive seeing as the higher-than-normal rewards suggested higher-than-normal difficulty, but it seemed about average for a one star rank 20 leve. The Kobolds were easy to take out one at a time, though all 10 of them start bunched up. I used Disorient to pull them away from the group one at a time and took my time killing them (actually trying to milk the fights for SP and EXP instead of just destroying them). I only died once when I got three links in a row without rest, but otherwise it was a breeze.
Naiya | Mithra | Windurst | Rank 10 | 1st Lieutenant | Ragnarok
WAR: 75 MNK: 75 SAM: 66
RotZ: O | CoP: O | ToAU: O | Apoch Nigh: O
Naiyah | B.Elf | 85 Rogue | Stormscale
Doubleday | B.Elf | 85 Paladin | Stormscale