It actually appears this does NOT work. I tried multiple configurations of the cables and disks 2 and 3 were never recognized. Either I'd get a E1A14 SAS A cable failure message and drives 2 and 3 activity lights would just never turn on (or be recognized in BIOS) or I'd get no error message, the activity lights would start green, but as soon as I'd go into the Perc6i config, the drive lights would switch to amber flashing and not show up.   As soon as I switched the SAS A cable for the one from my R710, the drives were recognized and no errors. Looks like I'll have to grab the RF5PF cable. 
After switching a Perc6i from a R710 to a R610 I realize I need new cables, which look to be RF5PF for SAS 0 and FTTNX for SAS 1. My question is can I use 2 FTTNX instead? Will they be long enough to reach from SAS 0? 
R610 Perc6i cables