Gordon looks interesting and I'm definitely going to check it out, but from what I can tell, one of the downsides is that it uses CF.
Don't get me wrong, I love CF for it's reproducibility, but waiting for a CF stack to run on every deploy will be frustrating for rapid iteration. CF is great for managing your infrastructure once you have a good idea of how it should look and aren't making constant changes anymore.
I suspect my workflow will be something like using Kappa while I'm iterating, and then using Gordon for the final deployment once it looks like everything is working as expected.