I had a Time Capsule when they first came out and had issues with it locking up and/or restarting by itself. I took it back and got an AEBS some months later. Now I use the AEBS with an external drive, which gives basically the same effect as a Time Capsule but runs cooler and bandwith is slightly less. It has worked pretty well for me running Time Machine from 2 Macs (the backups stall occasionally but I cancel and it recovers fine), but I use an external WD MyBook USB at work hooked directly to my iMac and it works flawlessly (and silently too I might add). Altogether I now have 3 of the WD MyBook drives and couldn't be more pleased.