Don't post twice in a row please, instead edit in the extra reply to your existing post unless there's more than a day between your posts.
Originally Posted by constantius
18% base mana for 1690 healing (15 sec)
+4% +15% +10% +5% healing and +20% of spellpower and -20% mana cost and -20% GCD and +initial instant heal (set bonus)
17% base mana for 1400 healing (15 sec)
+15% +10% +5% healing and +15% of spellpower and +initial instant heal
They heal for roughly the same per tick with the same gear level only if we Glyph for 4 ticks instead of 5. Additionally, Rejuv scales better with spellpower, costs less to put up, has a benefit (Swiftmend), and has less opportunity cost for casting the spell (GCD). Renew is still useful, but nowhere near to the same extent as Rejuv. But, then again, priests have a lot more tools to play with; druids are the kings of HoTs. A good comparison might be to consider what you would have to spec to pick up Healing Touch as a useful spell (as a druid); that's the situation priests are in with respect to Renew. Huge cost to get a marginal spell.
Thanks for listing all the modifiers. I didn't realize rejuvenation had so many modifiers in comparison.
The mana issue could be moot if you factor in mana free flash heals occasionally being cast from surge of light versus swiftmend. Also one question that might clear this up even further is does surge of light have a cooldown? If not it might be in some respects superior to swiftmend (mostly due to swiftmend's very long cooldown). If you have ~30% crit and are tossing out renews every GCD + 6 target CoH you have many chances to crit to gain the free flash heal more often than once per 15 seconds.
The one big drawback I can see is the shorter duration. 3 seconds difference seems small, except when you realize you can only cast renew on 12 people instead of 15 people (best case scenario, more likely 8-10).
I'll think about it and possibly try this setup and see how it goes. Thanks.