"reallocate" volumes would take a lot of time and efforts on all volumes, so, if it could really happen, I probably should sacrifice the opportunity to add 2 disks (~2TB). Agree?
Also, can somebody please tell me will these two new disks equally take incoming data along with 2 new raid group, if yes, then there should not be any hotspot, because there will be 2x22 +2 = 46 disks, enough spindles to stripe out data. Am I right?