I would suggest the second option. Files are easier to handle individually than image fields, and if you ever need to copy or move the data, SQL would have to go into hot backup mode, whereas your file system would be able to keep running as long as the file being moved or copied was not currently in use.
You will need to ensure you use a good file system for this. Also, you should use some sort of snapshot software on the SAN to help prevent damage to files through server failure. Copy on write is fine for this, but will limit you to under 10 snapshots per lun, and getting near that limit will reduce your performance to a crawl.
Netapp snapshots would be better for this because they don’t do copy on write and thus have no performance degradation per snapshot, but then you’re buying a very expensive box for files.