The Client Auto-Deployment basic workflow for a Release update is:
Epicor.exe (or Epicor64.exe) starts and picks up the specified Client Sysconfig file - for this write-up, “MyEpicor.Sysconfig” and referenced as the CL_Sysconfig.
Epicor.exe extracts the “deploymentServer uri” value from the CL_Sysconfig and then appends “\Client\Config” and attempts to fetch the file “MyEpicor.Sysconfig” from that path. If the file does not exist (and several attempts to read it are made using different Upper and Lower case versions), an attempt is made to fetch the “Default.Sysconfig” file from the path. Assuming we are successful at retrieving a file, that will be referenced as the DS_Sysconfig.
Epicor.exe compares the “version” value from the CL_Sysconfig with the “version” value from the DS_Sysconfig. If different, the Auto-Update processing starts else the login form is presented.
From this point forward, Epicor.exe uses the configuration settings from the DS_Sysconfig to continue the Auto-Update.
Epicor.exe (in the newer versions) goes through a series of file permission gymnastics to see if the user needs to have elevated Administrative rights to do the Auto-Update. If necessary, Administrative rights are requested and the user is told why Admin rights was needed.
Epicor.exe creates a Temp directory and copies all the local Client\Config *.Sysconfig files into the temp directory.
Epicor.exe extracts other deployment related settings from the DS_Sysconfig file (clearClientDir, etc.) and actions on those.
Epicor.exe extracts the “deploymentServer uri” value from the DS_Sysconfig and appends “\Client” and fetches “AutoUpdate.exe” and several other files needed for the Auto-Update processing and those are written to the local Client directory. Of interest here: any Auto-Update related changes made to the newer version of Epicor.exe do not take effect until the next Auto-Update sequence. Someone upgrading from 10.1.400 to 10.2.300 will be asked for Administrative Rights to do the Client Update because Epicor.exe in 10.1.400 required those rights for the update to proceed.
Epicor.exe invokes AutoUpdate.exe passing the DS_Sysconfig information and Epicor.exe terminates.
AutoUpdate.exe (now the latest version) continues the Client Update as directed by the information in the DS_Sysconfig - Zip file / XCopy / Customizations.
At the conclusion of the Update, the Local Sysconfig files in the Temp Directory are copied back into the Client\Config directory and the settings - except those in the “userSettings” section are updated to match those found in the DS_Sysconfig file.
AutoUpdate.exe invokes the now current version of Epicor,exe and AutoUpdate terminates.
As you can see from the above (and as referenced by @josecgomez), it is possible to move to a completely different Deployment Server by replacing the appropriate Client\Config\named.Sysconfig file in the current deployment with the updated sysconfig from the newer version. No other files in the original Deployment Server (as referenced from the original CL_Sysconfig) will need to be updated.