Yeah I'm a tad confused about this myself. Right now I'm working on gearing up a Resto/Ele shaman alt. I was about to buy one of the triumph rings when I realized that I'm unsure which will be the best post the Cata changes (and they work as a good example of what other choices I'll need to be making down the line).

Givens:

1.) Spirit is currently relatively useless to Shaman
2.) MP5 will go away and become Spirit in Cata
3.) Spirit will be converted to hit for Ele through some TBD mechanism
4.) Hearmender Circle stats that differ: Crit 50, MP5 25
5.) Band of the Invoker stats that differ: Haste 49, Spirit 50

So currently, of the two caster rings the Heartmender Circle is good for Resto, but neither is really good for Ele as they both have a relatively wasted stat. Now, let's say that the pre-Cata patch were going to drop tomorrow hypothetically. I'm confused by A) which ring would then become best for Resto, and B) would that ring also then be the best for Ele. My assumption would be that the MP5 on HC becomes Spirit, and the Spirit on BotI becomes Hit in order to keep the idea that there's a healer ring and caster dps ring. Do these changes mean that the difference between your healing set and your ele offset will be the relative balance between crit and haste most likely? I mean unless they are implementing some sort of Spirit cap, it seems to me that Spirit to Resto will always be good while Spirit to Ele will eventually cause you to drown in hit.