Reaper including utility has 8 ogcds.

Dragoon including utility has 12. So it is much lower.

It's very GCD centric and at high level you probably won't be using your standard combo that much especially in large groups where Death Design will give you souls per mob death. Along with Soul Scythe charges giving you 50 soul each as well.

It is worth noting that utilities/attacks such as Hellsgate(the warps), Harpe, Soulsow/Harvest Moon, Death's Design, Whorl of Death, Arcane Crest and role actions are all usable during Shroud.