As a lvl 70 priest, I see something very interesting coming in the next patch...
Empowered Renew: Your Renew spell gains an additional 5/10/15% of your bonus healing effects, and your Renew will instantly heal the target for 5/10/15% of the total periodic effect.
Glyph of Renew: Reduces the duration of your Renew by 3 sec. but increases the amount healed each tick by 25%.
T5 4p set bonus: Increases the duration of your Renew spell by 3 sec.
I am not a theorycrafter but from what I understand is that by combining the glyph and set bonus, you already increase the throughput of renew by a tick and a forth, so I am wondering by exactly how much will renew's initial heal will heal for.