What is the generally accepted practice for distributing new versions of the .exe and .dll files? I ask because the SAPgui versions that are available from SAP marketplace don't seem to get updated with the latest versions of the executable. Can the older files simply be replaced by the new ones?

Typically, the GuiXT version shipped with SAPGUI is not current with the version that is available from Synactive's website. In order to satisfy client expectations we are constantly adding new features and applying corrections to existing GuiXT software. If you are using SAPGUI version 4.6D and below, any guixt version should work. (However, we do encourage you to update the version for new features.) If you are using SAPGUI version 6.1 and above, you would require PATCH 15 for SAPGUI and GuiXT Version at least 2002 Q2 10.