I know what you're saying, and flirting with the five second rule is something I really enjoy on my priest, but for I'm adopting a wait and see attitude.
Ultimately, as long as I can still heal the fights I need to heal, I'll be happy. I don't particularly mind if I end the fight with 80% mana or 10%.
Also, I see this as kind of a response to the big buff our regen got before Lich King. I forget which patch, but there was one where they redid the way intellect affected the mana regen formula, and I saw a huge increase in both my OOC regen and my mp5, so in a way this a little bit of a return to the status quo.