Note that some Google's Debian Wheezy images are specifically optimized for their Andromeda SDN [1], especially when they running on us-central1-b or europe-west1-a zones, where Andromeda is enabled [2].

Also Ubuntu 14.04 LTS has much worse performance than Ubuntu 12.04 LTS, so it's better to stick to 12.04 LTS for now.

In my opinion it's better to port to Debian or to run Ubuntu image inside container hosted on Debian, until they will have native Ubuntu support.

[1] http://gigaom.com/2014/04/02/google-launches-andromeda-a-sof...

[2] http://googlecloudplatform.blogspot.co.il/2014/04/enter-andr...