Kev
like others here you seem to feel that the 'firmware update' method is somehow 'safer' than the 'bootable' method. That's not the case at all. Both involve loading CHDK into the camera and therefor involve the same risks (which are vanishingly small these days). The only difference is that the 'firmware update' method has to be used each time you start the camera.
Put another way, if you make the card bootable, lock it, put it in the camera and switch on, then switch off, you are in EXACTLY the same position as if you had used the firmware update method. And if you then unlock the card, when you put it in the camera and switch on, CHDK will not load and the camera will behave (indeed will be) just as it did before you ever played with CHDK.
The only reason people used to use the firmware update method was that making a 'bootable' card was a tricky error-prone process. Since it isn't now, I can't see any reason to use it.
