It has been my experience that SMB companies rarely find SAAS
architectures important and are not concerned with multi-tenant versus
single tenant architectures. In fact, these companies are often
adopting SAAS solutions as part of a business strategy to rid
themselves of technology issues all together. On the other hand, I
have also found that enterprise companies and organizations in certain
vertical markets such as Government and financial services are very
conscience of architectural differences and almost always prefer
isolated tenancy. When implementing an on-demand application, if you
have a choice to leverage your own autonomous database (isolated
tenancy) or share the same database with hundreds or thousands of
other companies (multi-tenant), I can't figure out why anybody would
choose that later and comingle their data.