The topology really shouldn’t have an affect on your migration unless you are moving from one topology to another. Even then the impact should be small – you just might have to do host-based migration rather than array-based. A host that can see both the source and the target can act as a conduit for the data movement. On the same topology, moving data from SAN to SAN or NAS to NAS, can <b>probably</b> take advantage of various array-based tools (clones, replicators, etc.).
Increasingly, we are seeing hybrid SAN array designs that support both fiber and IP (iSCSI) connectivity. Those are almost exclusively block-based storage rather than file-based like NAS arrays. There are even NAS gateways that store their data on SAN arrays, using IP connectivity from gateway to hosts & fiber connectivity from gateway to SAN.
I have really skimmed over the topic and introduced some others, but I believe I have answered your original question.
Please let me know if I can clarify or assist further.
Tools available are different.
There are two routes to migrate data. SAN based and host based. SAN connected data is easier to migrate via SAN
offloading your host and network. NAS connected data is easier to migrate via network using host based tools.