In the end, I went for the T4 Holy helm.
It will probably be the most useful for the next little while, given that I'm still Holy specced. As well, I did get a really nice weapon, and I should balance it out with some healing gear.
Finally, my previous healing helm was [Mask of Inner Fire], which is more a shaman DPS helm. Not to mention that it looks like Catwoman's mask, meaning the T4 Helm is a big upgrade in the style department.
I also got Exalted with the Shat'ari faction over the weekend, and picked up [Gavel of Pure Light]. My healing set is doing pretty well now. I'm trying to find someone with the Spellsurge enchant, but failing that I'll put +81 healing on it.