It's never lead to problems for me. However, some of my coworkers decided not to use c9 due to latency (which has never bothered me for some reason.)

I use the ssh-workspace feature and do my work in an EC2 instance. I've also been playing around with running a local c9 build (https://github.com/c9/core). Not sure that their license would make this viable for commercial work, but ofc there's no latency / connection requirement if you're running it locally.

Off-topic, you could even run c9 locally in a Chromebook if you were using Crouton -- and without having to install another desktop environment. I do most of my work on a desktop, but if I ever get together a mobile development environment this may be what I do.