Reply to USB 2.0 Too slow?

So I'm a recent guitarist -> controllerist convert and have never had to work with an external harddrive before. I want to pick one up but after doing some research I'm unsure about what to get. I've always been one to spend a little extra to get the sure thing so I was looking at getting something that utilizes Firewire instead of USB 2.0 (I'm using a new MBP 15" so no USB 3.0). I found the fancy-looking WD passport firewire edition to be appealing but there were a bunch of negative reviews about it being a CPU hog. The LaCie rugged seems like the only option but I'm trying to avoid it just because it just seems like such a hideous brick (I'm a fan of compact). If I need to I'll go with that but I was just curious as to how "slow" USB 2.0 actually is and if it truly impedes your ability to DJ well. I've seen several community s talking about it being too slow but I feel as though people just exaggerate, though I really don't know. Point being, I'd love to get a WD USB 2.0 passport or something similar if it's really not a problem (cheap and reliable apparently). But if it is an issue, LaCie rugged it is. Any insight would be greatly appreciated and my setup is in my sig, thanks in advance!