Just a quick update: I ran it last night at as a 1800 xp encounter, and while they thought it was a great fight, saying it was hard would be the exaggeration of the year. They had 1 person bloodied when it was over, and no-one had been really close to going unconscious at any point. In short, Irontooth got hit really hard, as soon as he poked his ugly nose out, and he never really recovered.
Actually, my players were great, they started out in a crappy position, but managed to turn it around superbly, and from there, it was just up-hill for the kobolds (and the goblin).
Cheers