The Flamebloom Gloves are definitely my glove of choice for Holy pre-raid, not sure about Disc as I don't use it much. Compared to Dolomite Adorned Gloves, assuming you reforge 67 of the Flamebloom Gloves' Mastery rating to Spirit and you use a Purified Demonseye and Reckless Ember Topaz in the slots, then the differences are:
Flamebloom: +38 Int, +43 Sta, +102 Mastery
Dolomite: +21 Haste, +53 Spirit
Compared to Gloves of Purification from the JP vendor, and using the gems mentioned above, the differences are:
Flamebloom: +28 Int, +43 Sta, +129 Haste
Purification: +63 Spirit, +28 Mastery
I'm at 3400~ mana regen in combat using Flamebloom Gloves, and I raid with that, so I'd definitely say you can do without the extra Spirit... especially when taking into consideration the extra Intellect boosts mana regen also. Although I guess this does depend on what else people are using in the other slots.