I have had some questions around Datalink on the ES400S. We have the same limitation with ES400S as with any other device that does not use DL in conjunction with Smartview.  Basically, the inability to support DL over the long haul because of possibility of slot 1 overwrite with network parameters if power cycled or reset.  If required however, per SEST, this can be still done manually via patch from Moto (due to a keyboard mismatch in the ##DATA values needed to manually program for DL). 
DL provisioning via OTA is coming in the near future (current target 3/20) which will resolve these problems.  In the meatime, if you have customers that require Datalink on the ES400S, please work with SEST at sest@sprint.com.