When would I change my Ripple client's Web Socket IP and Blob vault URL? What are the scenarios (value-add businesses) that would get users to edit the default ripple client and use a custom


Web Socket IP: Port
Blob vault URL


Why even make this a configuration option?  What is the envisioned benefits?  Is this related to a "gateway"?
The blob vault URL lets you choose who you trust to hold your wallet. While the wallet is encrypted, the organization that holds your wallet could attempt to brute force your password with the only limits being their computational resources.

The selection of web socket IP and port allows you to choose what Ripple server you want to connect to. The plan is to eventually let you have multiple servers saved in your wallet.

These choices have to do with how your client connects to the Ripple network and finds out your account information and annotations. It is not related to a choice of gateways, what IOUs you wish to hold, and so on.