I think a perfect scenario for using instances is when you have a single product that must be installed independently for individual clients.  So lets say I have a web project consisting of a web service.  This project will have its own web.config, global.asax, etc.  The docs state that sharing components among multi-instance is not supported so instead of being able to build a single.dll and sharing it among multiple clients, I have to copy that .dll over and over.  But I digress.

The idea is that since there are individual configs for each client, I need to have each instance of the project running in its own web application and I have yet to find a way to get Wix to do this.  I've read about instance transforms, but from my understanding, wix really doesnt support multiple instances.  I know SQL Server 2005 uses wix to manage multi-instance, but SQL Server 2005 is only getting installed a single time and the instance transform is making mods to the installed application.



It gets quite a bit more complicated when you have individual products (that are mostly identical) yet are not the same single install.  Modifying and removing individual sites with this approach seems daunting at best.  The matter is also complicated by the fact that instances are basically nested under the initial install inside the registry and I haven't been able to determine the ramifications, lets say, if I remove the initial install instance after adding additional instances.  Just feels dangerous to try to use Wix in this manner.

I like the ability to run via GUI or script, but in this scenario, Wix is making me nervous.