[andrew]

In my experience --- yes and no.

When pushing policy there is always a 'lull' in the traffic. Connections that can survive the lull stay up, those that cannot, don't.

For example, we have a telecommuter with VoIP and Instant Messaging over VPN. I can push policy while on the phone with this person, and the line goes quiet for a couple of seconds, and then we're back on, however the IM session is dumped and he must reconnect.

FTP over VPN dumps during a policy push, too. PCAnywhere over VPN, no.

Go through and test connections in your environment during policy push, determine what survives and what doesn't, and then you'll know what to expect when you make changes during the middle of the day.