Hello,
There should be no issues with booting from SAN using SFW 5.1, and as long as the hardware is supported by Microsoft, it is supported by SFW.
Note: If multipathing is being used, then you will need to check the HCL to verify the hardware is supported. This is not related to booting from SAN, but thought I would mention it just in case the customer was using or planning to use multipathing.
exftpp.symantec.com/pub/support/products/Storage_Foundation_for_Windows/302144.pdf
or just in case the link doesn't work: ftp://exftpp.symantec.com/pub/support/products/Storage_Foundation_for_Windows/302144.pdf
I hope this helps.
- Robert