When it comes to external firewire drive units, they are basically all exactly the same. Just about every single maker uses the Oxford 911 chipset and the same exact drives made by ibm/hitachi/western digital/maxtor/etc. The only difference between a LaCie external drive and a no name one is the case itself (ie. the fans and power supply in the case). The actual firewire portion and the drive portions are exatly the same.
As to the 1TB drive, as was previously mentioned there is no such thing as a 1TB external drive unit that is not using RAID to do so. That is where the cost is, in the RAID hardware.
Brian