Blessed Coldain Prayer Shawl: 20%
Spell Casting Reinforcement 3: 35%
Spell Casting Reinforcement Mastery: 15%
Total: 70% extention
If it was shawl only vs AA's + EE4 ya I'd go with the AA's and EE4.
Shawl with FT3 and AA's > AA's + EE4 IMO
FT cap 15 unless you invest AA's which maxes it to 20. FT20+Clairvoyance+Oak+alchemy potion(FT2 buff) = mad mana regen. Add canni5 AA and canni4 spell (or newer canni from OoW) and you get a killer shammy with a close to endless amount of mana.
Summary: Invest the time in shawl unless you are in a PoTime guild. If you are in a PoTime guild invest time in remembering you were once level 1 as well and come back to reality. Flags, Gear, countless AA's and max level are fine. Conceit and flaming on lower level chars is ignorance.