The glyph hasn't provided as much as I hoped, but a large part of that could be due to my crappy gear. The good news is that as their DPS scales, so will the healing. However, more than once I have considered not using the glyph and therefore not needing to use Seal of Insight (which is a DPS nerf).

There are lots of "smarter" ways to play - I'm trying it this way for the challenge. If I was trying to do it the "easiest" way I'd probably just go with 4 shamans and a pally tank, but that doesn't excite me. I was successful using no tank with 4 disc priests, though atonement heals a hell of a lot more than Battle Healer (so far), and I'm going to keep giving it a shot with no tank plus 4 rets. One of the ways I get mitigation is through 4 sacred shields, though it's not a ton. It will be a work in progress and I'm sure there will be a point where I'm hitting a wall, but it's not like I'm doing anything crazy like trying to take 5 mages through all the instances

So far the biggest roadblock, other than just having decent gear in general, is due to not having a magic dispel. If anything, at this point I will consider converting a pally into a healer for some boss fights just so I can get the dispel. However, I've avoided it so far and will try to do that as a last resort.