my big
worry is that these action surges are the main way to gain extra attacks on the fighter, just level up and eventually you'll get more double attacks per day. I'd much rather a theme such as TWF or some stance, granted by a theme, that gives you an extra attack (both at -2) and no str-bonus on each, but with an AC bonus if you are dual-wielding. Two swords is better defense than one, or a two-handed sword, surely. You don't open yourself up as much during each strike to ripostes if your swing goes wide or wild.
Daily powers I kind of don't like, but I hate encounter powers more. I don't want to see some artificial "encounter" delimitation that cuts the day up into 5 minute chunks. Encounter powers for martial characters made every battle the same, at least with dailies you have to chose when to use them. In 4e if you don't use your encounter power nearly every encounter, you've chosen the wrong one, which piegeon-holes you into repetitive tactics. I remember one of my rangers kept his offhand strike for finishing off a tough enemy that was near dead, this is cool but it got boring after a while. The optimal play tactic of 1 quarry / round meant I would hoard such powers for not only the BBEGs, but just to keep up my DPR / quarry damage each round in case I missed with both twin strike attacks.
But yeah, I can see 2x+ daily resources like this fighter surge thingy is better than a single time per day...and yes very much like rage rounds. But those rounds should be comparable to the number of spells wizards should get. I.e. if a wizard has 5 uses of prepared spells that can go boom, let's make this fighter surge thingy be 5x too. Or at least somewhat comparable. Or not.
Also, I don't see why he couldn't use 2 extra attacks, getting a total of 3, i.e. blowing it all in one round to finish off the dragon in an epic moment. Giving the fighter a REAL Nova round to look forward to, for when he has advantage on a crucial monster, would be uber to me.
One thing's for sure, this surge thingy looks like it will kill iterative attacks. I hated having different bonuses for subsequent attacks with my PF characters, but I would surely consider a theme in DDN that allowed me an extra attack every action, with all at a -2 and no str-bonus at first, then increase the str-bonus as you go up, and decrease the penalty.