In all the years we have known each other, I don't think we have ever disagreed Peter, just debated alternative points of view. I suspect the same is true now. I read your advice as suggesting the use of a config file specific to a purpose and I replied "retain a single CONFIG file because these are modified by versions of SAS, or even reinstallations on other PCs. I use alternative autoexec files for different purposes, autoexec for generic use, autobatch for generic batch etc.". So it seems we have the same reticence about changing the config.
However, I do change it for each installation, and all my version icons have paths to customised configs where I have set up my preferences for email, MsgLevel, FmtSearch and so on. I must also confess I modify below the line as well, by extending the Macro search path to include the macro libraries I have created for my or for group use. I then deploy the changed file to a SASWORK directory with other files available to one or all versions of SAS running on the machine.
Nonetheless, I define this change as "A THING TO DO VERY CAREFULLY" and to always retain a backup in case you overwrite the original. I noted for instance while updating a reinstall that the META-ID had changed from one install to another, so I carefully grafted my extra pieces on the new config and tested it.
However, please note I said that it is a config for a version, not for a task. I took your reply as suggesting configs could be at task level, and if I understood that correctly, then I disagree with that. I feel you might create AUTOEXEC, AUTOEXAF, AUTOBTCH and so on for different ways of using SAS and include application specific statements such as libraries and execution statements in the appropriate autoexec. I don't extend MgLevel and the other config changes into the autoexec because I think it makes them unweildy, and some of the changes I make are SAS invocation options, which can't be specified after the config.
As far as possible, IMHO, a config should contain those commands needed for every execution of that version of SAS, and adding options above the line should usually be safe. Then you do only have one config file for a SAS version.
Kind regards
David