I don't won't to jump to any conclusions but l just bought a PD 170 in AUS. even though l was expecting it to have the hum problem with the LCD screen, but at the moment l've only just quickly tested it and it seems like theres NO hum when l open the LCD or move it. But haven't yet recorded anything so l don't know whether that makes a difference or not.

If it hums, get fixed or get it replaceed. No sense in having this problem on an expensive new cam. One of the reasons I bought the MX300 a few years ago was because it has good audio.

Yes theres no worries there because l explain to the salesmen that l knew about the hum problem that was going around on the net and he stated that it is some sort of grounding problem to do with a screw and only takes about 15 min to fix and that if it was on my camera then it would be fix with no problems.
So so far so good.