Thanks for keeping us abreast of the latest developments regarding your healing strategy!
Originally Posted by Ferin
Just checked - they don't. Got hero from a shaman, popped PI, no change in spell casting times.
Good to know. This means I'll change how my cooldowns are used - saving PI for Divine Hymn (since I can't guarantee that lining that up with heroism will be optimal) and hitting Hymn of Hope during heroism (since, as long as the mana gained isn't wasted, it will aid longevity no matter when in the fight it is gained).
It will still be wise to have both cast under Borrowed Time.