I just went through all of this, so I'll give the pros and cons I came up with:
ASP.NET Web Site Administration Tool
Pros:
- Already built, debugged, and ready to go.
- Complete feature set. User can add roles, users, and security to their heart's content.
Cons:
- It's not really meant to be used remotely. It's meant to be used locally from VS. Microsoft's official stance is: yeah you can use it remotely, but we're not going to tell you how or support it when you do.
- Non-integrated. So, the user logs into my Silverlight application to manage everything EXCEPT for other users, where they need to log-in to a completely separate system that looks nothing like mine? It's not a great system.
Roll your own Silverlight Version
Pros:
- Completely integrated system.
- Relatively easy to code, once you get the hang of it.
Cons:
- I could not find ANY open source projects that did this in Silverlight. Why? Is it recommended against? Is it just not done that often? I hate feeling like I'm doing something few people have tried before.
- Not debugged nor full featured, and I have to do it myself. Just getting the ability to create users with two roles was lengthy (although not hard). But I'm concerned: did I introduce any security holes? It's difficult to tell.
In the end, I made my own Silverlight version. Too many people had complained about my 'hacked-up' version (as they put it), and it left a bad enough impression on people that I ended up making my own.