I like the idea of this pipeline. The only stopper to use it for me is BRE. I don't use is very much. For most of my requirements it is overkill. The only good thing is the rules could be changed at run-time. But this is not the Pro of BRE but Con of BizTalk.
BRE is overkill because: it requires study very specific model of development (it hard to create, test, understand, support, trace, debugg); a different deployment mode.
I'm not a single person. The BRE adoption shows that developers don't use it. The single place where I can see BRE it is the POCs.
That's my suggestion. If the pipeline framework functionality would work on the base of plain .NET dll, I would definitely use it.
C# is much simpler in development comparing with BRE. It is less known but it is also simpler in deployment (redeployment) in BizTalk.
Thank you for this interesting framework!