I don't personally know how high dps a Pugilist can do but i wouldn't say they were that much higher than MRD if higher at all, ARC i personally thought was very weak until i tested it tonight and after testing i wouldn't be surprised if ARC could keep up with MRD with the correct rotation.
The point is if you are doing 9-10k damage to ifrit per person you are either running with 3 damage dealers who are all doing 30+ dps which would be impressive and is why i said id love to see a parse of your breakdowns, or you are running with 4-5 damage dealers and your fights are lasting 10+ minutes, meaning the reason for the increased damage from each person is because of the amount of health Ifrit regenerates during the fight.
Our 5-6 minute kills generally put our damage dealers at around 6-8k damage per person when running with 5 damage dealers since the faster you kill the less health ifrit regenerates during the fight, i could post more older parses if you require proof of my claims but we rarely if ever see people with 9-10k damage total done to Ifrit unless we did badly.
Also Twenty Two (the person who played Pugilist on that kill) it was his first time ever attempting to play Pugilist on Ifrit which is mainly why he did the lowest.