Q:

Using Orchard for a LOB Application? 

Has anyone implemented Orchard for a LOB application?  If so, what was your experience?   Would you recommend using it or another CMS or do you think it’s the wrong way to go?  

A:

To my experience, developing a custom LOB application around Orchard may be a good or bad idea.  It all depends with what actually your are trying to achieve and most importantly what potential features/functionalities you want to leverage from the Orchard framework. 
Personally speaking, I fell in love with the Orchard modularized architecture and simplicity of the backend design.  I wanted to have all these features in my application and decided to write my application entirely on Orchard. 
So, if you want to make same decisions I made, I should possibly warn you about the followings:
1 - You have got to understand the MVC internals pretty well since orchard has a huge amount of code written in this arena.  If you are not that much of an expert in MVC, you will find yourself spending a lot of time figuring things out that you should. 
2- Depending what type of application you want to develop, getting rid of some of the built-in modules may be necessary, even some of the core modules which may lead you into problems that are hard to fix. 
3 - With this amount of customizations you make, any future release from Orchard will possibly break your code - and you may find yourself maintaining your own application framework and being unable to apply bug fixes and such.  And mind you, Orchard is just a new framework, so expect a bunch of bug fixes, releases very soon. 
Plus other possible ramifications, it is very important to weigh the pro and cons here before you make a final decision. 
So, my advice is a follows:
If you think you can use Orchard without heavily customizing its internals, you will surely benefits a lot.  On the other hand, if your project specifications are going to need you to make huge changes to the framework, then I wouldn't advice you to pursue this option. 
In short, for a seriously big project - don't use Orchard. 
Unfortunately, I am not aware of any other framework as well written as Orchard to recommend here. 
Hope this helps!