Glyph of Shield WallFollow

From the official 3.1 patch notes:

Glyph of Shield Wall: Reduces the cooldown on Shield Wall by 3 min, but Shield Wall now only reduces damage taken by 40%.

Combined with Improved Disciplines, this would give a 1 minute CD for a 40% damage reduction talent, which seems like it might be worth speccing for depending on the fight and your guild's tank setup.

I seem to remember though that this was nerfed on the PTR, and WoWHead lists the glyph as only reducing CD by 2 minutes. Any word on if this combination is viable, and any thoughts on it for progression fights?