Very nice post Zdenka. Our LS tried it the other day and I can concur everything that was said. Furthermore mixing ARCs with any close-range DD is very counter-productive. We initially tried a 2 ARC 2 PGL run and quickly found out why it was a bad idea. The second any ARC takes hate everything goes to hell. Moogles moving around are very detrimental to close range DD DPS as well as combos. When a Moogle is chasing an ARC they can't simply stay put either. Set aside the fact that they are squishy, they can't combo in close range.
Moogle is just a fight where the freedom of movement and ease to play of an ARC is just very desirable. In most other fights, however, ARC will rarely, if ever, be top DPS.
As for Ifrit after jobs release I'm pretty sure nothing will top MNK. Fists of Wind vs a fire-based primal. Game over.