I have some commentary.
Harvest Life for short aoe burst? Why not using rain of fire? It does more than twice the damage of harvest life. Mana costs are insane, but on a aoe burst window, too short for seed of corruption, lets say 5-8 seconds, this wont be an issue. Just try it.
Soul Link grants you 20% more hp if specced while using GoSac, more hp means more mana per lifetap which can result in less lifetaps per fight. Besides that, everyone loves big numbers. And having the same hp as the tank feels great :p
On fights where you dont need dark bargain as "oh shit" button, i would always specc into soul link when using GoSac.
Best race for affliction is troll now, just run some sims to check it. The mini bloodlust is pretty amazing for affli with pandemic. Not to mention fights like garalon and their 5% bonus vs beasts. With 4pc t14 and a little delay you can even time dark soul and berserking every time for some nice numbers, guess that would be a dps gain instead of using dark soul on cd.
And i spotted a little typing error: Below the t14 hc gemming table you wrote "340 mastery and 180 int". It is 320 and 160.