I have a kinda similar sorcerer grenado + canister bomb build, however I leveled it at least a year ago, it is sitting at lvl 85, with 5k hp, so very squishy glass cannon. 
Of course different devotion and item choices, but I already have some of the gear, so I just need to level it up and change it. I have to mention, that the grenado and canister bomb damage isn’t that magnificient, it can clear trash packs easily, and 2-3 grenados can bring down hero monsters, but bosses need some kiting. I use both of the Barrelsmith guns and I don’t have mana issues, but I used most of my components to reduce mana cost and boost mana pool and mana regen, but I can spam almost non-stop my abilities.
Regarding the theorycrafted build, I really like it’s tankyness, thats my main problem with my current setup. I was thinking about 4 pieces of the Ulzuin’s Avatar item set may be a good option, and for the medal there is the Kymon’s MI which can be vendor farmed at the secret vendor.
http://www.grimtools.com/db/items/7752
It is recommended to pick Skyfire grenado for this imo, to mix up our damage a bit, because fire resist mobs can be a bit of a problem. And I recommend to rather focus on grenado, because the canister bomb does it’s job of clearing the trash packs without too much investment, and the grenado is what helps us kill the bigger boys.
My question about the build is, we pick Star pact only for the 11% cooldown reduction? Maybe not worth it, but I don’t know.