Here's a pic showing the actual kill switch (my wife calls it a "Kill Bill" switch, because it's yellow like Uma Therman's outfit in "Kill Bill").
I also remembered two additional advantages of using a kill switch instead of the key:
1. If I'm signalling and turn off the key, the signal stops until I turn it back to Run.
2. Likewise, the DRLs turn off while the key is turned to Acc, probably making other drivers think I'm flashing my lights at them.