The reason why Iona and amilary sphere don't really work are simple: they are both very slow.  This will be a pretty quick format from the look at it, with red decks and soldier decks and jund deck's going crazy, I don't see this deck doing very well without a bane slayer to keep your life total high ad stop their offence.  I feel like regrowing giant angels every turn is a pretty strong play...the issue of course is getting that far into the game without red mana...I'm not gonna lie: this format looks pretty unfriendly to creatureless W/R decks...
Good luck.