Shutting down a VM through the new portal (portal.azure.com) prompts in a warning that the public IP address will be lost.
However, in this case the machine has a reserved PIP address which will not be lost. We are currently shutting down our development machine every night and the PIP reservation works. We have also a legacy machine without a reserved PIP which we cannot shut down since we would indeed loose the PIP which is used in our network configuration.
The warning is therefore misleading. The portal should check whether a VM/cloudservice has a reserved PIP or not. The same is true for the internal IP which is set to be static within our virtual network and will not change when the VM is started up the next morning.
Best,
Dennis