As I understand it, SL 6x contains the current SL implementations of TUV 
RPMs as well as specific extensions to TUV system that does not "break" 
compatibility with the TUV "stock" distribution.

Nonetheless, there are a number of other repositories for EL 6, many of 
which are mentioned on this SL list, and which address either 
shortcomings in TUV distribution or add functionality from other 
(enthusiast or enterprise) distributions.  A partial list that I have 
found includes ElRepo.org, PUIAS, ATrpms, RPMforge.net, Extra Packages 
for Enterprise/EPEL, and of course SL 6 itself (as well as duplicate 
packages from CentOS that contain the CentOS repackaging of TUV 
distribution source).  In several of these cases, software professionals 
external to the CERN/Fermilab SL staff are involved with the production 
of particular RPMs (e.g., Dag Wieërs if providing such a name does not 
have a similar taboo to naming TUV).

Is there any utility that comparatively will list what each of these 
repositories has and which RPMs are mutually incompatible?  For example, 
when I add one of these to the software sources list and then enable the 
addition, I get a large number of software updates (in some cases, a red 
badge with an exclamation mark indicating an urgent, probably 
security-related, update, appears on the top bar of the Gnome GUI). 
However, I am concerned that some of these "updates" will conflict with 
and/or "break"  SL 6x or packages from some of the other repositories.

Yasha Karant