I do not have any much idea but you can take help of this doc.
Regarding SAN and NAS I assume you have read and are referring to the techincal paper titled:
"WHAT IS THE DIFFERENCE BETWEEN SAN AND NAS AND HOW CAN I USE THEM IN MY QLIKVIEW ENVIRONMENT?"
In general it is hard to give an estimation of I/O required as it depends on many factors.
For the shared/PGO files it is generally driven by number of concurrent users and QVS nodes in the cluster.
For Publisher has been shown in tests that for a single reload more than 100Mbit/s not required for straight QVD loads (optimized), but with many parallel reloads (concurrent QVBs) each might consume up to that point. Loading data non optimized and from SQL or other sources obviously reduces this requirement.
Hampus von Post