MRD can definitely hold hate on single targets still. Damage is quite a bit better than GLA. The thing is that MRD's survivability is now significantly lower.

The attack debuff on Provoke isn't very noticeable, the increase in recast timers for Foresight and Featherfoot hurts, and the lower WS spike damage leaves you with a weaker Bloodbath. Sentinel is also 20% weaker on MRD than it was before and they also have about 700 less MP than a GLA. Rampage makes it so that they can only receive benefits when they straight-tank. Kiting is out of the question.

I think MRD is much better suited as an offtank now. It's great for picking off moogles and tanking them for the DDs to burn down.

Meanwhile, GLA has Aegis Boon on a 45 sec timer. This is an amazing ability. Against Ifrit for example, it can nullify the damage from a swipe and heal you for 700 dmg. That's more than Second Wind. Aegis can also block weapon skills.

Goring Blade and Riot Blade both do decent spike damage so GLA actually gets just as much use out of Bloodbath as MRD.

Only a GLA's flash can blind the enemy. Works much like FFXI's flash but is AoE and costs 0 mp - making it essential for kiting moogles.