* Heal Power bonus stacks, both are affected by elemental weapons (no surprise)
* Earthliving proc does NOT stack. Buff is refreshed.
* When glyphed, procced 179 times in 419 LHW for a 42.72% proc rate
As far as item comparison, it looks like it'll be the +63 SP vs +25 Int. I don't have resto spreadsheets set up to answer the is it worth it question.
You'd also tack on 195 +healing to the Paper Cutter since you'll get an extra Earthliving imbue, as you mentioned. I think that'll always give an OH weapon an edge over the best caster OH. Your test also seems to reinforce that it's two independent rolls, which will be 43.75% chance to apply per target. The question is: Will nearly doubling our Earthliving application rate ultimately prove more useful than having Earth Shield, Tidal Waves, and Riptide? If we're accepting that our role is 90%+ CH spam, perhaps.
I also noticed that the second point in Blessing of the Eternals loses some value in this build, as with one point the chance to apply Earthliving to a target < 35% health is already 87.75%. Whether the 2% crit is better than the point in Nature's Blessing is something to spreadsheet.
Going one (ridiculously huge) step further, I remembered an old video of an elemental shaman who used Mental Quickness and raid buffs to achieve astronomical spell damage values. We could sacrifice even further in resto and use Mental Dexterity and Mental Quickness to convert Int --> AP --> spellpower. Something like this
It's essentially twice the effect of Nature's Blessing, as well as converting all AP buffs (and attack power from offhands) into more spellpower. Yes, the change to buff stacking hurts this in a huge way, but I thought I'd still toss it out there. I'm pretty sure the loss of Improved Chain Heal is a bit too much though.