I could not find anywhere the answer to this question, although I direly would like the answer to be : YES !
If the “Dual Disk Redundancy” option is activated on a Drobo-S with 5 disks, does that mean that during the relayout and/or replacement of a single disk, the dire “Drobo cannot currently protect your data against hard drive failure.” warning is not pertinent anymore, for the long (2-3 days duration of the relayout ?
Solving this vulnerability issue during relayout would be for me the main/only reason to upgrade to Drobo-S.