The traditional passthrough (with no internal battery) needs 1.5 amps, but the X2 only needs about 0.2 amps. It doesn't draw vaping power from the USB port, it just charges the battery. They're two different things that work differently. The problems with zapped motherboards and what have you I believe referred to the traditional (no battery) passthroughs.
In choosing between the X2 and the Spinner, I would pay the little extra for the Spinner. I'm sure it's an anomaly, but the last X2 I got runs a little hot and burns my cartos. If it were a Spinner, I could just dial it down. On the flipside, T3s seem to work better for me on the hotter X2 than they do on the other ones, so sometimes it's nice to be able to dial it up too. I'm eventually switching all my batts to Spinners, and the only reason I don't have one yet is because the colors I want don't come out 'til March.