Originally posted by JailbreakJacob
why wouldnt you?
USB read speeds are simply alot slower than SATA speeds. USB also puts some stress on the CPU (I've noticed this more if you are using a USB header and not the ones that are actually right on the board) and it's bandwidth is shared among all usb devices that are in use.
If that's all you have for now then by all means go for it. It won't hurt anything and you can easily move those installs to a new drive later if you choose to do so.