The difference between healing a WAR and PLD is very noticeable, lacking the damage mitigation of PLDs it can be surprising how big the chunks of damage they can take with each hit.

But even with that, if you had to spam cure to keep a MRD/WAR alive it's almost certainly a bad tank. You'll be surprised at how some tanks take tanking way to literally and soak up all the heavy damage aoes instead of dodging them.