I may have missed what you were asking - if you have spent millions implementing an ERP, you are attempting to use an ERP strategy over a "best of breed" strategy. This may be the motivation behind your CIO comments. If this is the case, your departmental applications should be dumped entirely and the business processes involved should be modified to fit the "best practice" processes built into the ERP. Where a department really has requirements for a separate system (this is a much rarer situation than most people think - especially in SBU's) a supportable interface to the ERP should be deployed. You are now supporting a hybrid ERP/BoB (which to some degree is often the case at most places claiming to be an ERP shop).
We deployed PeopleSoft here in 2006 with help of a third party partner - through diligent procedural development wehave become self sufficient even through major upgrades. A constant threat to our success has been the reluctance of process owners in the SBU's to even consider changing their business processes to match the vanilla processes delivered. More than once we have had to wait until a major decision maker retired to change processes only to find out the the new processes, after an initial painful adjustment period, are superior - better suited to our needs, easier to integrate, adapt better to changing requirements from users and governments, scale well and are easier to monitor and report on.