>>If you depend solely on SPs for your backend, the middle-tier would be at the
>> very least redundant, and at the very worst, ignored.
>
>Huh? what school of DB design and application development taught you this?
>

I think you are ignoring the distinction between a business tier and a data access tier. With SPs, the Data Access tier lies in the database, with other techniques, it can lie in its own component.

You mentioned in another message that your business components can deal in XML "if your backend supports it". By this I guess you mean features like SQL 2000's new XML features. Well, if your data access tier was its own component, you don't have to depend on the backend to produce your data in XML, your data access tier can access the backend in whatever way it sees fit (ADO, SPT, RV, whatever) and produce the XML for consumption by business objects and/or UI Proxies.