Adventure: Your CF and DotNet code are working great and talking on your dev server and integration server but not on test or production? Error says "Class xxx not found in the specified assembly list". Even though you can call built in dotnet methods, so the CF .Net integration service is working, you can't call any of your assemblies.
After comparing, trying and reading many, many, many things. The final solution was to uninstall and re-install the CF 8 .Net integration service. There is an install on the Adobe ColdFusion product downloads page. I found the solution on this forum post.