when u speak of sata enclosures, do u mean pc card to sata to ide bridge? If u can get that, then it should have more speed available given that its 1500 compared to firewires 400. However, those are just numbers, as everyone knows that usb2 is 480 but generally doesn't come close to fire for sustained rates.
I've burned at 8x no probs on firewire. When I tried to rip a movie in a borrowed 165 tho, my cd speed graph maxed out at 10x. I don't know if its the drive, the disc or the bus being stressed. It shouldn't be the bus, but one can never tell.
firewire is good enough for sustained transfer rates of MBs in the 30s range. Fire is great for hard drives. I only know of fire 800 on new macs.