Have this ever happened to anyone?
 

Has ANYONE every crashed as a result of using a "suicide hub" (aka fixed cog on freewheel threads) when they WERE USING BRAKES and NOT trying to skid or trackstand?

In other words, you're just riding your fixed gear like a normal bike and the cog came loose and somehow locked up the wheel and made you crash even though you had brakes?

Can't speak for anyone else, but I always ride this way and I've never crashed as a result.
The main danger people refer to is not being able to stop, but if you have brakes that's moot.
I've also had my rear wheel lock up for various reasons at completely unexpected times, and I've never crashed from that either.

as long as you can pull your foot out of the toe clip and ted shred to stop you really don't have to worry.

**** man, ride brakeless if you want.