That's the approach we take, documented at http://www.boxever.com/gracefully-shutting-down-haproxy-with...

The challenge is that whether HAProxy's own support for graceful restarts works depends on which OS and kernel version you're running and what network socket features are supported, so ensuring that's all kosher is a bit of a challenge. I took the approach that it's simpler to do something that takes a bit longer without having to worry about all that.