Hey guys and gals, I'm in need of a new external hard drive and all I need is the drive really, I have the case already. I've been looking at some WD Black drives and there is a 1TB for around $110 with 32MB cache and a 1TB (newer) Black 1TB for $140 with 64MB cache. Now I'm not doing crazy editing but still, would like the best bang. Is the $30 extra really worth the jump to 64MB cache? I'm plugged in via Firewire 400, running FCPX on a i7 iMac with 16GB ram.