I haven't used the Gravity, only tried it on in the store so I can't compare the breathability.
I have put several hundred miles on a Driclime and pretty much agree with everything Gary said. It's plenty breathable for everything I've used it for and simplifies my layering system for cold weather winter hiking. I also use it a ton for summer dayhikes as a "compromise layer" - a little insulation, a little rain protection, wind protection, good breathability, and bug protection without the need to carry anything more. The hood does suck.
The Gravity, I suspect, would be much warmer and would be more challenging for me to fit into my layering system. I appreciate that I can keep the Ether on pretty much the whole day whereas I suspect I would have to add and remove the Gravity more often depending on the temp.