The original 40GB HD from my 1st player works in both players. The newer 80GB HD does not work in either. Therefore, despite it not being an Apple model, and despite other people having been able to upgrade to 80GB with no/few probs, this HD must for some strange reason not be compatible
Having said that I've just logged on to the Rockbox site for the 1st time in ages, and noticed the response you referred to. I'm pretty sure I've done this procedure at some point in the last 3 months, but will do so again just in case...and will let the world know if successful!