Hi Ade,
I had also believed that piece of propaganda from the AC-DC wars - but when I looked into it I found that it is not based on science.
The "can't let go" current threshold is again much safer with DC. Here's a reference with a table showing DC vs AC loss of muscle control threshold, and the required current is roughly 4x as high for DC.
http://www.highvoltageconnection.com/articles/ElectricShockQuestions.htmRegarding AC vs DC for long distance transmission; 1M volts DC is being used in lots of countries and between countries. The under-sea line between Denmark and Sweden, is one, as I recall. It eliminates the sync problem between countries power grids, and DC wires can be smaller for the same voltage drop since there's no dead time between polarity changes. Conversion efficiencies are quite high- comparable to AC.
Westinghouse won with AC because there it was no technology for efficient DC-DC conversion or DC to AC conversion. For the level of technology of the day, it was a rational choice and it made Tesla's 3 phase motors for industry viable.
Casey,
Lot's of things do work on 120VDC, and many more can be modified to do so. Bimetal switches can't be used for switching 120vdc, so the classic duty cycle temperature control or thermostat won't work. What I did for my toaster oven, for example, is to add a MOSFET power transistor for each element, and let the timer and thermostat control only the tiny gate control voltage (resistively derived from 120vdc). That way the transistor does the switching and everything works nicely. No power supply is needed and only a rewiring of the thermostat and such. Many things like crock pots and immersion heaters or even hair dryers and coffee grinders, blenders (the last three with brushed universal motors), and soldering irons work fine without modification. The 120V "universal" motors run equally well on DC, since they are actually DC motors.
I don't seriously think we will have a switchover to DC power anytime soon. There is a huge vested interest with AC. More likely DC will happen with independent power systems as it is now for data centers.