Understanding throughput in general is a concept that will apply going forward into the next expansion as well, though not necessarily in the same form.
As a healer you have four throughput stats, and the potential of a fifth through talents (if you have talents which make Spirit a throughput stat, not the case for Shaman).
Your four stats (for throughput) you care about are...
Spellpower, no functional limit, linear growth rate indefinately.
Haste, soft and hard capped.
Crit, soft and hard capped.
Intellect, converts to crit at a low conversion rate.
Those are your throughput stats which will effect your HPS.
The general rules for healers tend to follow this.
Haste (Below Soft Caps) > Spellpower > Crit (Below Soft Caps) > Haste (Above Soft Caps) > Crit (Above Soft Caps) > Intellect
Most healers will fall into this general pattern as far as throughput is concerned. Please note this doesn't take into account any concerns about efficiency (this is approaching healing like a DPS would, I don't care about efficiency, just want as much as possible in the least time). Crit and Intellect are probably higher in priority because of their value to you as an efficiency stat.
To answer your question, if you're above both crit and haste soft caps for your abilities, the maximum throughput can be reached by going for straight spellpower.
This is coming from a balance druid who would heal on dreamwalker in balance gear to have significantly higher crit. Dreamwalker is the proverbial case where a healer cares most about throughput and least about efficiency.
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.