It also depends on how much interaction you need with fellow developers, the client, or any other technical resources your staff provides.

Myself, I routinely test new features with the client, need to consult with our system administration group or database group or just need to coordinate some development with other developers. Some of this can be done by e-mail just fine, but if my hours are 4-hours off-sync with the rest of them, I may end up waiting for certain things to get finished or answered.

In addition, if shit breaks, managment will be infinitely happier if I am on staff and on the problem than if they have to call me at 10am and wake me up. They might decide to hire someone else to be available when I'm not, and it's just one step from there to outright replacement.

But it depends totally on your work environment too. If you have a fast link from home and have no problem hopping on as if you were in the office, "off-time" might not be as "off" as it might be for other developers, so it might not be a problem. It really depends on the criticality of your position and of the applications/systems you support and how many others are around at any given time to pick up the slack while you're out.