I meant more specifically stocking up on healing items, spells and talents - since they don't actually make your fighter any more durable except in responding to abrupt damage spikes, which his high constitution equips him to soak and fix up with CR (which i'll concede although irritatingly good at draining your Health, is essentially 'free' healing spells. Its more that actual healing spells stink. Using your example:
You hit 200 endurance with Eder around 6th level iirc. Since you're applying the 20 DR only once I assume this is from a single strike or effect tick? A healing spell available to a sixth level group (Moderate Stamina) restores from say Durance a pitiful 26 endurance . That's a third level spell - of which you have only a couple - to undo a single three second tick of damage. Or you could use that 3rd level spell for Despondent Blows, drastically cutting the incoming damage at source which if we're measuring over the lifetime of the spell (healing being a one-off benefit) adds up to a great deal more time to live. (Repulsing Ward, 2nd level, even more effective at stopping things from hurting you). Similarly the first level spell Armor of Faith grants 4 universal DR, a 20% increase on 20 DR. This grants the same fight-duration staying power as TWO level 3 heals (4 DR, applied to 10 'ticks' over thirty seconds = 40 damage prevented) AND reduces the loss of Health since the damage was never taken.
My summation is that outside of very narrow circumstances, healing is just an extremely sub-par use of resources and the Fighter doesn't bring enough to the table to make CR and its 'one-fight-Eder' stylings when you compare it to the other viable front liners. CR is 'free' but its bad at coping with sudden spikes, keeps turning off your resistances, makes you rest more frequently while a paladin with Strange Mercy and Lay on Hands can dish out a lot more punishment, has better defenses to stop damage at source and can snap their fingers and jump back from death's door with per-encounter powers. Anyway, thanks for the breakdown you guys! Helped me to figure out where I stand and why I was side-eyeing Eder and his perpetually failing health.