I like this idea and I've been building towards this pre-patch. Even with only 100 Dex at the moment, my level-151 AB's cast time is really awesome.
My gears at the moment: +12 KK Chibi, AA Blush [Also, a Dark Illusion Blush for the -10% cast time], FAW with spells, Temp Dex Boots with Muscle Fool & Spell5, KBC RWC pendants with spells, Recovery Light Wand with spells, Orleans's Gowns [for a faster cast time than a phen card]
Here's my planned build: 130 Int, 120 Dex, 77 Luck (for AA), 79 Vit. As you can see, high-healing is still important for me. Bear in mind that this build is for PvM/MVP support. I can't wait to see the instacast high/coluseo heals, sanctuary and safety wall on this one.
As for carrying capacity, I recommend people who can afford it to just use heavy lifter tickets. If I had any stats to spare, I'd personally put my points in Agi to lessen the animation delay.