I have a DGL4500 as well. The wireless covers the entire house with 100% signal strength. It also covers most of our block lol.
The only thing I don't like about is that the GameFuel table limits the number of QoS rules you can make whereas the 4300 I had dozens of rules setup.
EDIT: Heres our wifi coverage overlay, and this was tested on a POS Wireless-B adapter