Personally I was thinking more
this.
My thinking:
The 51 point talent for Chloro is just another way to use charge, and you already have 4 others just within the Chloro tree. Wild Growth pretty much does what the 51 pointer does (fair enough without the damage component) and Chloros already have enough spells to be dealing with without needing another 2min CD.
The 3 points in Unleashed Abandon and the point in Empathic Bond are pretty meh; UA is a PvP thing, and EB is a tiny mana return, when there are plenty of other easy ways of getting mana back. Taking 6 points in Ele gives you an OOC evocate, which solves any mana issues and keeps drinking downtime low.
Within combat the Archon tree gives you 10% mana return every 30s, 2.5% mana back on crits, all abilities 4% cheaper FOR EACH AURA (you'll likely have 3+ at any one time) - as well as giving all those tasty buffs.
The only thing you're really missing from the other build is the extra charge via the 'lock soul, and the 10% chance of insta-cast. Personally, I've found most of my healing (granted it's lower levels) comes from the Lifegiving Veil and Synthesis, and spot healing is mostly unnecessary, making the reduced cast time rather meh. The lack of extra charge might prove a pain, but I usually find I have sufficient charge, it's not something I tend to run low on.
But you're the one with a max level mage, and the one who's running the high level dungeons, so my argument is pretty moot until I can compare