Toxikon has the same effect that Dosis has on single target, and it is just plain better on multi-target. Eukrasian Diagnosis is going to break on the Tank a lot. So much so that you will rarely have time to hardcast a Dosis. Phlegma is alo better than hardcast Dosis as well. It is hard to even consistently keep up Eukrasian Dosis with Eukrasian Diagnosis can break so often. You have to take some time to cast Eukrasia before getting off a shield too. Honestly, I kinda feel Eukrasia is a bottleneck that could easily cause serious mistakes. It reminds me a lot of the old Dark Knight Dark Magic spam issues. A lot of SGE gameplay relies so much on Eukrasia that you won't be hardcasting a lot.
This all means that a SGE rotation looks more like this (regardless of amount of targets), by proc:
1) Toxikon
2) Phlegma
3) Eukrasian Dosis (if you can)
4) (hardcast) Dosis / Dyskrasia (if the tank is not taking serious damage)
This will only change when you are leveling and you have some upgraded spells but not others.
SGE DPS is like WHM but backwards. WHM builds up to instant cast spells from hardcast spells and SGE does the reverse. Also, Dyskrasia feels only slightly better to use than Art of War, and only because of Kardian. You also have so much movement because of Toxikon that if you don't have room for Icarus on your bars you shouldn't feel bad not using it. I also hope that Eukrasian Dosis splits off into its own spell in the future. It feels pretty awkward to consistantly keep up compared to the other healers because you have to use Eukrasia first. I find that Eukrasian Diagnosis breaks by the time I want to refresh it and, therefore, I don't because the tank suffers a lot if I pick Eukrasian Dosis over Eukrasian Diagnosis at that point. And than, because it broke, my next GCD usually becomes Toxikon if there are any number of adds.
(I may be off on some information, but that's how I took in SGE DPS this morning.)