Atleast all of my business logic is there in very clear form. I don't really feel confident. Reverse-engineering or hacking is other thing as this is way too easy to steal the hard work.

I tried this by making simple windows forms application and publish it. I select The application is available offline as well. It generated setup.exe and subdirectory Application files. Under that there is file application.exe.deploy I renamed that to be application.exe and open it Lutz Roeder's reflector. It was able to re-generate my source code from that. I think my clients can do same.

I like C# but its useless in my applications because I can not protect my source code as its always included in deliverables. Is there any real solution coming for this in near future or should I just give up C# .NET. I believe this should be major concern for many but I haven's see Microsoft taking any role for this.