As a healer, high 630's is perfectly fine for normals, but your raid has to be somewhat competent, as you can't really compensate for as much fail as you're used to. You see it every expansion: at the start everyone feels underpowered, because they can't kill shit before people start dying. As a result, they start bitching their dps/hps is too low and Blizzard fucked up class power. However, that's just bullshit.
What's really going on is that people are sucking at the game. Tanking and dps is mediocre because people aren't good enough at new stuff yet (encounters, talents, abilities, etc.), they take tons of mechanics-damage, and the healers are not well geared enough yet (or good enough) to compensate for all that fail. As the expansion progresses, you see a healers get more mana/power and they start compensating for all this fail (this is not because of awesome healer skill however, 'compensating for fail' just means healing more).
Obviously, this effect is much more pronounced the lower on the foodchain you get.
What's really going on is that people are sucking at the game. Tanking and dps is mediocre because people aren't good enough at new stuff yet (encounters, talents, abilities, etc.), they take tons of mechanics-damage, and the healers are not well geared enough yet (or good enough) to compensate for all that fail. As the expansion progresses, you see a healers get more mana/power and they start compensating for all this fail (this is not because of awesome healer skill however, 'compensating for fail' just means healing more).
Obviously, this effect is much more pronounced the lower on the foodchain you get.