The first time D+Z implemented CRM, they integrated customer master data from ECC; however, this ended up polluting the CRM system with bad / messy data. The problems ranged from incorrectly formatted addresses to customer names in ALL CAPS. This hurt user adoption and gave a negative image to external customers.
D+Z didn't have the time nor resources to clean all the data in ECC, so the second time around, they cut the connection to ECC. Now, the Accounting department owns customer master data in CRM (and ECC) and makes sure it is clean & accurate without duplicates. Sales reps fill out a Sharepoint form that is workflow enabled to request the creation of new accounts.
Session: "Case study: How Day & Zimmerman applied its own CRM implementation lessons to improve a later CRM upgrade"