In 18s it works, but you get more healing from throwing in shelter if you fist heal. If you leech then using anima vessel or just throwing in RnS is better. In Hell Eternal the DPS will often have killed themselves on the shield by the time the ability finishes, in the ankh it can be useful when you use it on the pillar, though I tend to tell the DPSes to time their jumps, or use a curio/heal potion instead (Guess I am lazy that way). In SH it can prove fatal as the bosses hit hard, and frequently, cold blooded is a better option whether you leech or fist heal In Fac you generally have a healtank, and if not then you have a leecher who should use anima vessel, RnS and/or veteran as the leech healing done then scales with the massive damage boost from the nodes, and finally, in HF, it simply takes too long to cast unless your tank runs a massive amount of physical protection, but since most of us fist heal HF anyway, having shelter slotted should be possible.
The only scenario where I find the quantum bracelet to be useful, and even preferable to other aux weapons (A whip with a mod is great as a healer in dungeons, it lets you give your group a damage boost with giddy up, throw in jones in the fast lane and the cooldown is halved thus making it a rather frequent damage boost at that) is in scenarios when I heal survivors in NM.
Edit: As stated here:
http://www.tswdb.com/miscellaneous/auxiliary-weapons/ the quantum brace can be combined with a charge signet to make it a heavy hitting weapon against two targets, though it can be a pain to aim.