Why upgrade to R12.1? One valid reason is support.
As announced by Oracle during Open World 2012 here are the key dates to consider for Oracle EBS 11.5.10 support.

Extended Support ends in November, 2013.  In December, 2013 11.5.10 clients will enter sustaining support.  For the first 13 months of sustaining support you will receive exception support for the following areas:

1. New fixes for Severity 1 production issues,
2. Critical Patch Updates (CPUs), up to and including the October 2014 CPU,*
3. United States Form 1099 2013 year-end updates (for Oracle Financials/Accounts Payable product), and
4. Payroll regulatory updates for the United States, Canada, United Kingdom, and Australia for each country’s fiscal year ending in 2014.

* POST OPENWORLD ANNOUNCEMENT: Exception for CPUs until October 2014 is newly added feature as of October 29, 2012.

Avout can work with your business and IT departments to plan the upgrade. Avout’s resources average over fifteen years of implementation and upgrade experience.  Our engagements typically last from four to six weeks and provide the following services:

1. Upgrade Envisioning – Focused interviews, workshops
2. What’s new – Review of new functionality available in R12 and technical changes
3. Project Scope Definition – Deliver a project scope document based on prioritization of requirements findings and gaps
4. Presentation of Findings – Deliver R12 recommendations and findings to key stakeholders

For the latest information on Oracle EBS support details, please visit MOS or Steve Chan’s blog.