First of all, I welcome everyone's comments on ELs. I did refer to the DMG's advice on ELs and the strength of the rogue ambush was a result of that. I'll continue to use ELs as a guide or at least as a 'second opinion' on anything I think up.
Henry, yes, I'm using a mat and counters (I don't have the time or room for minis any more).
And Forrester, I understand your surprise, as I shared it. I have to admit though, while the rogues did pick their targets, they could not all attack the same individual. The characters were - please, please forgive the hackneyed device; I was still warming up - escorting a small trade caravan, actually riding on several of the wagons. The deployment of the rogues meant that some could attack those at the front of the caravan and some could attack those at the back. Coupled with this limitation were some extremely unlucky rolls. The attack began with three thunderstones being hurled at the caravan, two at the front wagon, one at the rear. All the PCs had the temerity to makes their saving throws. The sneak attacks left one of the characters bleeding to death at the end of the first round and another disabled but stable on zero hp.
However, the cleric (who wasn't easily identifiable as one and therefore wasn't among the initial targets chosen by the attackers) immediately got a cure light wounds (at +1 caster level, because of his Healing domain) for the maximum 10 points on the dying character, while the druid managed to reach the unconscious character and deliver a cure minor wounds to him in the same round.
After the first round, only one rogue managed another sneak attack and that was on the fighter, who survived the paltry extra damage roll and then sliced the rogue in two for his impudence.
Anyway, again I thank you for your advice, warnings and consideration.
I will raise a glass to you all forthwith. My goodness, what an uncharacteristically good idea.
