My company is about to undergo a large project in which our client wants a large customer portal with a cms, crm implementing. This will require interaction with data from multiple sources across our customers business, these sources include XML office backend systems, sql datbases, webservices etc.

Our proposed solution would be to write an API in c# to provide a common interface with all these systems. This would be scalable for future and concurrent projects within the company.

Our client expressed an interest in using Biztalk rather than a custom API for this integration, as they feel it is an enterprise solution that any of their suppliers could pick up and use, and it will be better supported.

We feel that the configuration work using Biztalk would be rather heavy for all their custom business rules which are required and an interface for the new application to get data to and from Biztalk would still need to be written.

Are we right to prefer a custom API solution above Biztalk? Would Biztalk be suitable as a databroker layer to provide an interface for the new Customer portal we are writing. We have not experience with using Biztalk before so any input would be appreciated.