I've been dabbling with this myself lately, for multiple reasons.
I'm currently using Cloud9 and frankly I can't tell much difference performance or feature wise (but I don't extensively use all the bells and whistles in any IDE anyway).
Cloud9 is cool because while you can use their servers to really quickly bring up dev environments, you can also just as easily SSH into your own box (I'm using AWS with Bitnami distros) for flexibility and security. You get convenient access to the files in the IDE just like it was local, plus any number of shells. And you get unlimited access for $20 a month.
Also, bringing a new developer online is super easy, and it makes for easy live collaboration.
The only disadvantages are that you need a decent internet access all the time, which can be a problem if you are a road warrior, and for me when I'm doing mobile app development with ionic framework the live update feature doesn't work, as well as launching the mobile app on the device from the shell (since its not directly connected). But that's pretty minor.
Being able to get good performance out of a lower specced machine is also nice, because it means I can custom build something and still do the same dev...