I joined my startup 2 years ago on-site. After my wife and I had a baby it became very difficult to live in the bay area. Housing is obviously ridiculous there and I had to live an hour away from the office. I told my manager that we would be moving and I was interviewing for remote jobs. They ended up allowing me to work remotely, and I have been for almost two months now.
The whole transition has been much smoother than I could have ever imagined. My team relies on slack so I definitely feel just as connected to everyone. We do regular video calls on Google Hangouts, and even have a robot[1] that makes daily standup fun and convenient for everyone.
I feel like I am able to focus for longer periods of time being away from the office. There are no distractions to play ping pong and interruptions are fewer and farther between. I also have much more time since I'm not commuting ~2 hours a day. I have time to spend with my wife and 1-year-old and I have time to go to the gym. I feel much more well-rounded as a result and I feel like I'm a better father and husband, and a much better employee. Overall, I think my output has gone up and my productivity has increased, though I have no data to support it.
[1] http://www.doublerobotics.com/