I have reforged out of spirit for the benefit of haste or mastery and gemmed/enchanted full intellect and haven't had any major issues running out of mana on any boss. We're at 3/6 normal HoF on 25man, but haven't started heroics yet, where things may be different...
I'd have to check in game for my stats, but at the moment I'm ilvl 485 and have about 4.3K haste, 18% mastery and 15% crit.
I'm not sure, but I think I have about 4K spirit left I couldn't reforge out further.
The haste is just enough to get another tick on WG when windsong haste proc is up (9 instead of 8 without SoTF - 13 instead of 12 with sotF).
This allows me to have very high burst aoe healing when needed. I only have to be carefull not to spam when it's not really needed.
The rest is management of personal and raid mana resources.
It does get tight at times, but that is usually because dps is taking avoidable damage or the fight takes longer because too many died.
I don't believe we should stack more spirit to accomodate for that, but grow as a team to do the encounter right on all fields.
With a spirit build I end up low on the healing meters and don't contribute as much during aoe healing phases.
With an intellect build I'm in the same range as paladins and priests, sometimes performing better, sometimes worse.
Resto shamans usually are the highest. Monks should be generally higher as well, but we haven't got a good monk in our raid team at the moment to show for that.
I realize there is no number crunching here to support this, but all I'm saying is that it's not only stats, but also how you play and use the mana you have available to stay competitve while being efficient.