Resto shamans generally have more mp5 because shamans are chain casting.
I think part of the way they intend to "fix" the mana regen issues (since downranking is something almost all shamans do) is with Improved Water Shield. Personally, I'm not a fan of this talent.
With water shield, my shaman currently sits at ~150 mp5 and 1750 +healing unbuffed - and my gear isn't even half epics yet. I generally don't have mana problems, though.
All the tips I've been given have been to put Mana Tide down early, use your pots as soon as they are going to give you benefit (not when you NEED them, because they won't be off cd when you're oom).
The only spell I downrank is Chain Heal from Rank 5 to Rank 4, and I do well enough. Last week, I went to Mag's in a pug, and not only topped healing charts, but also was #7 on overhealing - behind all the other healers and the spriest. And still had mana to res a few people.
Currently, as far as I can tell, devs are trying to give shamans more versatility with main healing, but the meat of shaman healing comes with raid healing (and the same can somewhat be said of Holy priests).
As for not having HoTs, I'm not sure that really matters. Though, in its current form, Gift of the Naaru kinda sucks (scales with 100% of +healing, but also on a 3-minute cooldown, has a cast time, and doesn't heal for much). I use GoN more on my warrior at the start of a pull than I use it on my shaman during a pull.