The problem with this thread is that
red shirts only died in 13 episodes (and fewer
red shirts died than there are posts in this thread so far).
If we include the pilots, here are the casualties from TOS (by episode and uniform color)...
Oddly enough, it seems that the idea that
red shirts died a lot in TOS is based on people assuming
red shirts died a lot in TOS. Watching the show doesn't effect this preconceived idea for most people because everyone is constantly repeating it.
I'd have no problem wearing a red shirt on the original Enterprise based on the data (though taking a vacation during the second season wouldn't be a bad idea).