The drive removal from one slot and the insertion into another slot will require BIN loads on the array, and will most likely require two BIN loads: one to remove the drives from the Disk Group (drive deletion in the bin) and one to add the drives to the Disk Group.  Those operations will handle the necessary details you are concerned about. The drive deletion from the bin requies the full config lock during the CCA review, but the drive addition can use the no-lock bin load process for hardware only upgrades.
As we are all aware one of the most important aspects of running a VMAX is balance.  Long story short we have a VMAX that is very unbalanced between BE processors for the SATA tier.  With the v1 hardware and 4 engines, 8 directors, there is a total of 32 BE processors.   The first 3 engines have between 9 and 14 drives per BE processor, engine 4 has 2 drives per BE processor, and is cold most of the time.  How hard would it be to drain some of the disks from the first 3 engines and physically move them to engine 4 and add them back into the disk group And rebalance across them.  Let me know if this makes sense.  -sean
VMAX 10k balancing