Data taken from the EU forums post, hoping to get a response here:

http://eu.battle.net/wow/en/forum/topic/1695060234

Basically, it looks like dots are ticking for 8% less damage, and only does the same damage per tick with ISF.

Quoting from Hrensgory:

Check Dóctor's logs on for example Cho'Gal a day before 4.0.6 and on 4.0.6
destruction, same encounter same boss one day later:
4.0.3
http://www.worldoflogs.com/reports/rt-nkn2zo98zh9i6531/details/24/?s=13164&e=13589
4.0.6
http://www.worldoflogs.com/reports/rt-q7job9y46khzr7ct/details/12/?s=7239&e=7645

Remember in 4.0.6 he have new ISF that increases spells damage by 8%. Every spell got damage increase with exception to:

Burning Embers - correct according to patch notes (damage reduction of Burning Embers)

Immolate and Corruption
4.0.3:
Immolate 113 4514.5 510144 36 10202.4 367287 04:53 (69.0 %)
Corruption 111 2432.5 270003 38 4780.7 181665 05:13 (73.5 %)
4.0.6
Immolate 72 4544.9 327231 35 9196.7 321886 04:15 (62.9 %)
Corruption 96 2369.4 227458 34 4502.9 153100 05:02 (74.3 %)

And remember - as destro, Dóctor have 8% ISF buff on immolate corruption - take that 8% off and see what is non ISF buffed ticks/crits on immolate/corruption for him now.

We're looking at per tick damage, since with the loss of the haste buff, we obviously lose overall damage from the smaller number of ticks.

Anyone here have logs to support/refute this theory? Would especially be interested in logs from any Demo locks (imm/corr) and afflocks (corr).

[Warlock] Immolate/Corruption Stealth Nerf?