For trolling forum readers, let's get the title of this post out of the way. The DevForce Object Mapper does not break a Prism application. Nothing in your tale indicates that the mapper is causing trouble.
DevForce helps you build, maintain and persist your business model. Prism helps you build compositional apps. These technologies contribute along different dimensions and hardly intersect. DevForce cannot interfere with the RegionManager.
I can find no mention of "UnityContainerExtensions" in the code. Perhaps you mean UnityExtensions which are standard issue Prism. That's where the UnityBootstrapper lives. If you intend to use Unity for dependency injection, you're going to use this assembly. You must use some kind of container if you are using Prism.
The loggerfacade is standard Prism. The Gateway for encapsulating the EntityManager is our recommended pattern but not required; the likelihood that this has anything to do with views not showing in regions is near zero.
There are too many moving parts in your question to provide an answer. Can these technologies work together? Yes. Are there any known problems integrating them. None to my knowledge. That might be comforting but it's not an answer.
My sense is you are throwing all the ingredients into the pot at once and hoping it works. That doesn't happen often enough in my experience.
I recommend a more deliberate process. Start smaller, ask intermediate questions, and answer them ... with tests ... as you go.
I would back up to the point where things seemed to work. Go all the way back. Make your view bind to a fake business objects. Get it working.
In a separate solution, I would make my DevForce business model work ... with a minimal UI. Forget about Login for now; do that last. Get a working Silverlight DevForce app running.
Then bring the DevForce business model into your silverlight application solution but do not hook it up into your application in any special way. Make sure it is still functioning.
I wish I could tell you precisely how to bring these together. I don't know what the "Best Practices" template is. In fact, I am suspicious of anything that bills itself as such. In any case, I do not know what pieces are involved. I know that you will have to solder together the sections that are in your app.config (Silverlight side) and web.config (Server side). If you are using app.config to configure Prism behavior of any kind, maybe you overwrote those sections of the config. Who knows. You'll have to look carefully and move slowly, verifying as you go.
I would create a simple layout view ... the simplest view possible ... and make sure that my Prism app can show that view. It should have nothing in it. It should show in the region just like any other view in your app.
Then I would take the DevForce model and make it appear in that view. Forget the Gateway and MVVM. Do it straight up in the code behind.
When you have that working, refactor.
Edited by WardBell - 08-Feb-2010 at 10:38am