If you want to compete and downwind in 2017 and beyond and you can only afford one board, why wouldn't you get a 14'? Will there be any races in this country that are restricted to 12'6" by the end of this year?

Get a 14.

Same, 14'. You'll get frustrated very quickly on a 12'6.

Get the 14 you want regret it. Pick up good second hand on seabreeze

NNSUP said..
You can certainly compete on a 12'6", however, nearly everyone else your racing will be on a mimimum of 14. Downwind races here such as the Cut and races in Sydney are going unlimited in addition to the 14s. Some races will just be unlimited. You'll certainly see the difference f you're on a 12 footer. There are plenty of good and cheap 14s around. You'll regret buying a 12'6".

Ditto NNSUP
I started my downwinding on a 12 6.
With a 12 6 you'll catch one wave at a time.
With a 14 you'll hook one wave onto the next one or two.
With an unlimited board you'll hook up even more waves. The extra waterline adds speed and lift, so they just keep accelerating. With enough wind and waves it's like a magic carpet ride.

Like Suzie says "there ain't no udda than a board with a rudda"!