Of course, you need solid foreign keys and cross-references that support integration and reporting, but that's infrastructure. From a user-experience point of view, there's a virtue to us vs. them.
The meta-lesson here: CRM is a representation of user culture. To serve its business purpose, it must have high adoption by sales and marketing users. Mixing in the process discipline of accounting into the culture of sales, where "it only has to be good enough to make the sale," will undermine — at least in the short run — the effectiveness of your CRM system.
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