Is it a vaible option of not?
There is no requirement for high reliability. Failed messages can be resubmited by the source party.
BizTalk scales badly, so the idea is to multiply the simple BizTalk environments in the independent "pipelines". Load Balancing can be implemented on the IIS (or something similar) because the inbound messages are delivered with SOAP / REST / HTTP.
What are the issues with such architecture?
Leonid Ganeline [BizTalk MVP] BizTalk and 0MQ (ZeroMQ)