I've felt the Smite pressure so immensely that I didn't even really give Disc a fair try without Archangel. I kept hearing from everyone around me that all healing priests will need to take Archangel for the mana regen, even Holy priests. At which point I kind of gave up.
Meandering around the blogosphere, I ran into a post at Murloc Parliament about just this. I stand in solidarity with you, Zel. I'm respeccing once Cata hits into something I feel more comfortable with (less Archangel unless there's no better choice). I will play the game the way I want to. That's what I did in BC. It's what I did for the most part in Wrath. There are other ways to maximize mana regen than using Smite. I will find these ways or die trying.
All is not lost. While I still feel that Viva will be my main, there is still hope on the Priest front.