So the blue post said:
- Adjustments to curtail powerleveling and boosting.
Curious how this will be handled. If instances will give experience as they do in Classic then even 1.25x quest experience will not change the leveling “speed” as most optimal will be instance farming, especially if you can do it efficiently.
If instances will be cut down then “optimal” leveling will be through questing in the open world, often with other players 
And 1.25x will just compensate for some exp lost from instances.
Prior to TBC I leveled a Paladin from level 1 (with TBC quest exp and bit lower exp requirements 1-60) and at level 60 I had like 2,5 max level zones of quests not done - where as I quested with only some instances: like 5 SFK, 10 SM, few higher level dungeons and then at 59+ we farmed like 20+ Scholos to push other palas in guild to 60 (got exalted Argent Dawn…). All other exp was from questing - leaving majority of EPL, most of Winterspring, bit of WPL, all UBRS/LBRS quests, some BRD quests not done. One of guild palas that did solo ZF and alike leveled quicker than me.
SoM will have vanilla exp requirements, likely much less instance exp so IMHO leveling won’t be “fast” - unless something gets discovered or the instance exp not changed (and only boosting exp and mass pulls).