You’re talking about the issue you described in this topic, right? How do I load FX files?
If you can share a shader that fails for you I’ll take a look. You’re missing out on a bunch of nice things and bugfixes if you stick with 3.5.
EDIT: I think the problem might be that you’re not setting the GraphicsProfile to HiDef? That would cause a SharpDX exception when creating the shader. For everything above 4_0_level_9_3 you need to set the GraphicsProfile to HiDef. This isn’t documented very well and a lot of people have run into this 
I quickly checked the code for your deferred rendering engine and noticed it doesn’t set the GraphicsProfile so I thought this may be the issue.