That's not true, you can definitely move a SAN and have the replications continue from where they left off. Search the Compellent knowledge center for "CSTA - Preparing and Moving a Compellent DR Site". That walks you through the process of RE-IPing, etc. If you use Async anytime there is a Replay of a replicating volume, it queues that up to be replicated. There are not separate Replays to accomplish this. 
I was told by Compellent support that if a replication link is broken, or if the SAN is re-IPed, replication must be setup again from scratch.  Is that the case?  If so there's no point is trying to presync a SAN before sending it to the DR site.  It's almost hard to believe the system re-sends every bit of data if a link goes down or if you re-IP one of the SANs. Every other replication tech I've used would rescan but that doesn't necessarily mean all data would be resent. Also, they never answered this - if I used Async replication does the SAN use separate replays for that or does it use the regularly scheduled replays?
Replication - presync before moving SAN