We've got at least 10 in guild right now in various stages of development.
Big difference regarding amp is I'm a high 80s AC tank (damned chattering ring), you're a low 90s. That 30% healing amp is huge. I also tank epics stuff all the time where I'm pretty much an evasion-barbarian so the high HP and healing amp makes it easier for my hjealers.
Does he have lightning resistance? The Artificer can cast the spell for Adamantite DR bypass. Though with the short life-spans tanks will likely have I suspect you're better off just keeping the Mineral IIs in your hands.
Holy Burst Adamantite of Great Construct banes for all my mooks is next on my crafting list.
I guess it depends on the toon, I just haven't found a better option on mine that doesn't include icys.