The PERC H710, H710P, and H810 cards support migration of virtual disks from one controller to another without taking the target controller offline. The controller can import RAID virtual disks in optimal, degraded, or partially degraded states. You cannot import a virtual disk that is in an offline state. Disk migration pointers: • Supports migration of VDs from PERC H700 and H800 to PERC H710P and H810• Supports migration of volumes created within H710, H710P, or H810• Supports migration of volumes created on H310 to H710, H710P, or H810• Does not support migration from H700 or H800 to H310• Does not support migration from H710, H710P, or H810 to H310 [URL]
I recently purchased a Dell T620 and got a H310 instead of H700 SCSI controller (was trying to save some bucks).  I'm finding that the H310 just isn't handling my load (several dozen Hyper-V test machines) compared to the H700 under similar conditions so I was thinking I could "ugprade" to a H700.  Is this even possible? Would I have to do a complete rebulding of the machine?    
Can you "efficiently" replace a PERC H310 with a H700?