Arlaren
Veteran
Decided to test this on my 39 warrior as I hate questing and never turn anything in. Turning in the quest 'Challenge Overlord Mok'Morokk' which rewards me a Duskwallow Impaler gave me the following results. Out of eleven turn ins I only achieved one upgrade from blue to epic. Please see spoiler for comparisons. Upgraded epics from blue will scale from ilvl 45 to 51.
Live:
View attachment 10623
PTR (Scaled to ilvl 45):
View attachment 10624
PTR (Epic Upgrade):
View attachment 10625
Seems pretty significant. Unfortunate.