And if your buddy happened to buy 4 of the damned Knights, becuase he liked the model. And then you're all poo-holed.
But after about 10 games, I've found that I can usually handle 2 as an uphill battle.
Flyers are still handy, but for some reason less balls-out amazing than they were in 6th. I can't really quantify why, but their overall power level has dropped a bit. Except for Storm Talons, that were already good and then got smacked with steroids this go-round.
The DA dex is quite good. I had a chance to flip through it quickly. "Bike" types are very well suited to 7th edition, at least in my meta, and DA have... the best? 2nd best? Bike units in the game. Refer to re-rollable Jink saves, coupled with Skilled Rider. And then look at the skimmer that boosts nearby cover saves.
2+ Rerollable cover saves = hilarity ensues. Sure, your shooting then kind of sucks, but those Raven Knights of Doom get a useful cc weapon, and you can always give the sarge a Pointy Stick, or something. Oh, and Hit and Run...
And Necrons... and the Post Decurion detachment rules. 7th gets unglued without a sense of restraint these days.