I have EVERY battle class to 50 and I've done Ifrit with a few different classes and I can say.....

Glad is STILL the best tank... without question....
The most HP.. the best defensive abilities (Which may be cross class but Glad have longer times and shorter cooldowns with them), full use of Provoke (pound for pound the best hate getting ability not counting cures or damage) and the use of a shield, which, even if it doesn't proc as much, its another piece that can have materia added to it, materia like +70HP or +20 defense.... The only thing MRD does over Glad is damage. And damage is a viable hate holder... but still... thats what your DD is for. In the long haul, Glad beats MRD at tanking....

Lancer is THE BEST DPS.... Mrd hits the hardest but is TOO SLOW to one on one out DPS the Lancer, or even the Pugilist for that matter. Gear, Materia, weapons, abilities and players skill level all influence your DPS....
Lancers with Speed Surge and Pugilists with can do more DPS... trust me
Also the MRD has higher HP and uses heavy plate with more defense, so it's possible the MRD had to spend less time healing himself... Honestly, most of your parties Damage was low as crap... I have parsed the Ifrit battle fr dozens of fights... many of them wins.... (and MANY of them loses)... I can assure you.... Lancer does more damage....
And honestly, the dated banneret lance BLOWS
Ifrit Harpoon, Champion's Lance or Hart guisarme for the win....

Marauder does the best AOE damage.... but they are super slow.... once all three of your regular abilities are on cool down and you have no TP... you will sit looking at the screen for days waiting on your character to do something... anything... that is your balance... Slow hard hitting MRD, lower hitting, but super fast and crazy critting Pugilist or the balance of Lancer, that is decently quick with Speed surge and does really good damage with Doomspike... and can damage a crowd if you know what you're doing

So MRD own at the beast strongholds... let them have their shiny moment... Every one will have their place to show their stuff