Tier 4 Ageless gives you a bit over 20% global recharge on average, and tons of recovery or debuff resistance.
DA can certainly be endurance hungry due to Dark Regen, and so can Mace due to Clobber.
Mains (Freedom) @Auroxis
Auroxis - Emp/Rad/Power Defender Pylon Video Soloing an AV
Pelvic Thunder - SS/Elec/Mu Brute
Sorajin - Elec/Nin Stalker
Neuropain - Sonic/Mental/Elec Blaster
Thanks for the info! I didn't know about the debuff resistance, that sounds interesting as well.
My Characters
Knight Court--A CoH Story Complete 2/3/2012
Well i had the same issue for a bit but I decided on taking spiritual and ageless on my fire tank. I know it is an end hog as well as dark is but with 1 minor difference consume comes back up fast but some times I do not even need it. I do not know what build u have to compare it too.
If you're having occasional issues with endurance, adding more recharge to the mix will only add to the problem. Personally, I'd go Cardiac and then go Ageless.
@Rylas
Kill 'em all. Let XP sort 'em out.
Cardiac is nice for any resist based set (can up your survivability significantly, especially if you have Tough as well), and when you add an endurance hungry set like DA... Cardiac seems like a no-brainer. Spiritual is nice and all, but your heal is back up fast with DA, and it's quite strong already (assuming you slotted it well, which you should have). You can get more recharge from other places, too, so I'd say Cardiac.
I do have a Rare Spiritual for my Fiery Aura tank as well, but I prefer the added survivability and end usage of the one with Cardiac.
Guide: Tanking, Wall of Fire Style (Updated for I19!), and the Four Rules of Tanking
Story Arc: Belated Justice, #88003
Synopsis: Explore the fine line between justice and vengeance as you help a hero of Talos Island bring his friend's murderer to justice.
Grey Pilgrim: Fire/Fire Tanker (50), Victory
Thanks everyone! I think I really knew that Cardiac was the better choice for her, but you all helped me feel better about the choice. 
My Characters
Knight Court--A CoH Story Complete 2/3/2012
I finally have enough shards to alpha my Dark/Mace tank, and now I have to decide which one to get.
I had originally planned to get Spiritual for the recharge bonus, but even though I have Physical Perfection on the character, sometimes her end bar dips to the half-way point when I'm soloing. With Cardiac I'd get a bit of a resistance bonus too.
I seem to recall there's a Destiny option (Ageless?) that has recharge...has anyone looked at that to see how effective it is? I'm wondering whether going with Cardiac and then picking up my recharge bonus in the Destiny slot might be a viable alternative.
Any experience, advice, etc., would be appreciated!
My Characters
Knight Court--A CoH Story Complete 2/3/2012