In terms of changing the controller-scape, Avalon can only be mentioned as a detail to Bitmaintech, for all the good things Avalon that may be. I can not see the appeal of a Pi ZERO over Bitmaintech's chosen BB derivative, not even price (and not to mention connectivity, or the lack of it - USB to ethernet considered).
if your good at doing custom oases on any pi, give it time you will be able to use any type Pi, you want with Avalon's,with bitmain you can but can' t, you take a very big risk of messing up that new 1.7 k US miner, not just the controller, if you try some kind of modded controller in place of there BB, you all most can't mess up any miner with a stand alone controller that uses one, so the benefits of a stand alone out weigh a built-in one any day.
I have brick a few bitmain controllers the miners still worked but it was disabled/useless till i could get a replacement controller, it made me want my own off unit controller.
with Avalon's it's just a mater of setting up there openwrt server on another PI type. it's very possible and safe to do.