Glyph of Dark Soul really isn't a good DPS glyph. You should be using Dark Soul on cooldown, and delaying it for anything is a DPS loss (unless you KNOW that something better is going to line up - for example, not using it on CD during the pylon phase of Elegon, delaying it until the platform comes up and you begin your assault on him once more).
As for Soul Link, Soul Link works backwards now, as well. If your Felguard takes damage, you also take that damage. This usually isn't a factor for things like AoE damage since he takes 10% of that, but for direct hits, you will feel it, too.
Grimoire of Service is only a beneficial option over Grimoire of Supremacy if you can line up damage on an extra damage phase that happens every 2 minutes or so. Otherwise, it's an on-use ability that if you are not using it perfectly on cooldown, the damage will fall behind that of Supremacy.
When you don't have any trinkets lined up, you'll want to use about 200-300 of your Demonic Fury so that any DF gained isn't wasted, until your trinkets line up again. However, Affdots also works with Demonology and not keeping track of the spell power on Doom would be a HUGE DPS potential loss as you can have Doom up for 90 seconds. Spending a global to power it up to 180% of its original power under Metamorphosis would be a silly thing to pass up. Using Touch of Chaos in Meta form does NOT change the spell power of the Corruption ticking. It only extends the duration to the max, so charging up a powerful Corruption before going into Metamorphosis is a noticable DPS gain.