It's an interesting time in the Oracle E-Business world in that we're drawing closer and closer to the end of Extended Support Fees being waived by Oracle for EBS 11i. The extension ends in November 2011. The waiver of the fees for extended support was a goodwill gesture by Oracle given the current economic climate. Having said that, the extension date is fast approaching and only about 10% of Oracle E-Business customers have upgraded to R12. Incidentally, EBS 12.0 will transition from Premier Support to Extended Support on February 1, 2012. To be eligible for Extended Support for EBS 12.0, customers will have to apply the EBS 12.0.6 Release Pack. So, as you can see, there's a domino effect, in terms of cost, for not upgrading.
From personal experience with ERP customers, the longer one puts off the inevitable, the more painful and costly the eventual upgrade can be. One of the reasons for this is that the skill sets required to upgrade from an older version of ERP X to the latest and greatest can become harder to find, thus increasing the cost of the upgrade vs. having done it in a more timely manner. Another factor to consider when upgrading is the concept of upgrading vs. reimplementation. Some of the factors to consider in this comparison include the age of the existing application. For example, in some of the research I've done, I learned that organizations who where on, say EBS 11.5.8, opted to reimplement vs. upgrade due to the amount of work involved in upgrading from such a dated version of the application. In addition to the age of the application, the choice to reimplement was made in part because of the change in the way in which those organizations did business. Meaning, they determined they had many outdated and inefficient processes that were easily eliminated by a reimplementation and would eventually result in cost savings and add to the ROI of becoming current on their application version.
While I admit that some of the abovementioned information may be considered common knowledge, I have had conversations with folks at trade shows and such who haven't considered these fundamental questions with respect to upgrading their application environments. The reason, IMHO, is that there is a plethora of information available out there and a million and one topics on the subject of upgrading EBS. It's pretty easy to drown in the sea of information available. One site that I found to be very helpful and has a lot of easy to read and easy to follow information is https://blogs.oracle.com/stevenchan/. The information seems to be very well thought out with links to additional topics throughout the blog that give one a lot of food for thought with respect to upgrading EBS to R12.
If you're in the process of upgrading, I wish you all the luck in the world and hope you really, really like coffee... =). Going forward, I'm working on a document that talks about how Stat can help alleviate the pain of upgrading; primarily, through the use of Stat's strong CM and Version Control processes. As you read through the abovementioned blog (link), you'll find that effective CM processes and controls are a key aspect of a successful upgrade.