Need an external backup drive of somewhere between 2-4TB. I have older hardware with FW 400/800 and USB 2.0 ports. But I'd love to future proof myself for when I upgrade and buy an external with FW800/USB 3.0. Of course this costs $200 vs $130 for 2tb. Is USB 2.0 good enough for simple backup or will FW800 make a big difference in real world usage?