I dont see how you can think this is bad for disc.
This proc procs from:
Prayer of mending
Power Word: Shield
non dmg penance
This, if used right is acually awesome for disc. Halo and divine star produce a serious ammount of overhealing. And if used right you can just pop PWS like 4 times and get the proc pop halo and spirit of chi-ji hits for 900k-1mil. Its simple really. Tried it out of LFR ToT today and it worked like a charm. Ppl say it produces around 1-4% healing done but i easily got to 6-9%. Since it procs from PWS you can basically choose when u want it to proc during an encounter unless you want to try to get it to proc all the time. Just wait like 45 sec and try some PWS then it procs. This is acually awesome for disc. Although its only good if you either spam atonement during the proc (low overhealing though) or if you time it with halo and atonement. For a fight like f.ex lei shen. If u use halo with the proc on thunderstruck it easily heals for 1 mil. And there is lots of fights with that kind of mechanic or high overall dmg going out.