Are there any fundamental differences between the configs applied to the SRP521 & 527?

The reason I ask is that there seems to be more options disabled from the "cisco" user (once the Xnet config is loaded) on the 521 than the 527.

On the 527 there was a Web Access Managment section in the Admistration settings where http/https access, as well as disabling WiFi admin access could be configured. This doesn't seem to be accessible on a 521.