Post by Dunsinane
3.0.1? No. 3.1
Source...(lots of stuff about Spirit mana regen)...
Since paladins rely less on Spirit as a mana-regeneration stat, we have to address them in other ways. We don’t want to change Illumination or Replenishment. However, we are going to increase the healing penalty on Divine Plea from 20% to 50%. Divine Plea was originally intended to help Protection and Retribution paladins stay full on mana. It should be a decision for Holy paladins, not something that is automatically used every cooldown.
In addition, we are also changing the way Spiritual Attunement works. In situations with a large amount of outgoing raid damage, as well as in PvP, this passive ability was responsible for more mana regeneration than we would like. We want to keep the necessary benefit it grants to tanking Protection paladins, while making it less powerful for Holy paladins in PvP or raid encounters with a lot of group damage.
...(stuff about clearcasting and balancing healing classes with each other)...
If you read the whole post, mana regeneration across the board is taking a hit. Spirit will no longer give as much mp5 when under the 5-second rule and most mana recovery strategies are being affected. They are definitely trying to make mana conservation an issue.
To answer your question, "It depends". The nature of the fight is going to determine how much you can sacrifice healing output for mana recovery.
Intellect will remain the best all-around stat for Holy paladins, but the balance will shift somewhat for fights where a constant high output over time is critical. Until we see Ulduar, we can't make claims with any accuracy.