"It is common now especially with SANs to use Snapshots and CDP" - Is it!? Snapshots yes, CDP no way, how many use that other than banks, and banks willbe making damn sure they have good backup processes in place.
"but any block level changes would mean an increase in the replication traffic" - Block level changes are occuring all the time, snapshots won't make a difference and the snapshot size only increases if there is more changed data since the last snapshot.
"we still need to defragment as fragmented volumes take considerable time to backup" - this does not apply to all SAN technology, certainly not Netapp.
If the section on Snapshots/CDP is anything to go by then the not only is the article rubbish, but the original research behind it probably suspect.