Firewire drive enclosure issues

It seems not all firewire drive enclosures are equal. Those with an Oxford 911 chipset apparently work properly with OSX and you can boot off them. The one I got today from Maplin was unfortunately not an Oxford chipset but a Prolific PL3507. It works ok in so far as it mounts the disk in OSX but trying to boot from it doesn’t work – it just hangs and doesn’t find it. Time to find a different one.