Anti-Unification? Communication, Workflows Matter Even More
If all this points you away from consolidation, what's the alternative? The first order of business is to give users extra visibility into records outside of their CRM instance. Typically, this is just reports or read-only views, and the answer is either a data mart or some clever query writing. If you can keep the use cases for this cross-system visibility fairly narrow, costs can be pretty well contained.
To make all this happen across multiple systems, you need to develop common system administration practices, development tools, documentation (gasp!) and at least a weak form of customer master. There are tools to help with all of this, but the first order of business is a common set of management principles and incentives that will make the multiple systems work over time as an effective federation. Too much laissez-faire and you'll see those multiple systems collapse into cacophony and confusion.
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