You have of course all seen the new Grey Knight/BRB FAQ. Plenty of people have gone over it in detail. What I want to do is quickly examine how the rulings effect the the viability of running pure Draigo Wing lists.
The same psychic power's effects can stack.
I didn't see this coming - especially with the wording of Might of Titan explicitly stating that it stacks with Hammerhand. This means that Draigo, a Librarian and the squad can all cast Hammerhand, and the Libby cannot course cast Might of Titan too. Strength 8 Halberds should become a relatively common occurrence. It also means that multiple castings of Psychic Communion can stack their modifiers on reserve rolls.
Psykers cannot try to cast the same power twice.
This prevents Draigo from using Psychic Communion twice in order to keep troop units in reserves until much later in the game. A minor inconvenience at higher points levels, but this really weakens my preferred strategy at low points levels, where single Paladin squads make a very handy second troop unit.
Grand Strategy makes Dreadnoughts scoring.
Despite my earlier ruling to the contrary, we can now use Dreadnoughts to hold objectives. This is an absolutely perfect fit for Draigo Wing - with usually only the two scoring units, and these being forced to move forward in most scenarios, the ability to hold those back-field objectives with Psyflemen is a godsend. Make them Venerable and watch your opponents struggle to nullify what must now officially be one of the best scoring units in the game :)
Dreadknights don't double their strength from the Nemesis Doomfist.
The Shunt move granted by a personal teleporter cannot be used when Scouting.
Don't take a Dreadknight - take a Venerable Dreadnought!