Please find attached the cisco definitions. Only the GD will show without some kind of threatening info regarding the level of code maturity. An ED is quite safe to run. The LD or the EXPERIMENTAL are quite more instable. The deferral cannot be found on web and if you have any you better move elsewhere. In any case, since you are running 12.0 I would suggest a GD like the 12.0(26).
Sorry if I posted the whole definitions, but I could not find a link not requiring login and I suspect you do not have software centre access privileges.
Fabio
Deferral (DF)
The purpose of the Deferral Advisory is to announce the removal of affected IOS image(s) from Cisco's offerings (i.e.CCO) and to introduce its replacement IOS image(s). At the time that the Deferral of an IOS image is advised, customers are strongly urged to migrate from the affected image(s) to the replacement image(s).
Early Deployment (ED)
Software releases that provide new features and new platform support in addition to bug fixes. Cisco IOS CTED, STED, SMED, and XED are variations of ED software releases.
General Deployment (GD)
Date at which this software release reached the "General Deployment" milestone in its lifecycle. A Major Release of Cisco IOS software reaches the "General Deployment" milestone when Cisco feels it is suitable for deployment anywhere in customer networks where the features and functionality of the release are required. Criteria for reaching the "General Deployment" milestone are based on, but not limited to, customer feedback surveys from production and test networks using the releases, CE bug reports, and reported field experience. Only Major Releases are candidates to reach the General Deployment milestone.
Limited Deployment (LD)
A Major Release of Cisco IOS software is said to be in the "Limited Deployment" phase of its lifecycle during the period between initial FCS and the General Deployment (GD) milestones.
