In my world, audio came first, video followed - now they are used together.
It isn't so much that the high definition models are "better suited for sound" - though it does seem more than a coincidence that the four models all happen to do high definition (and there do not seem to be any other sub-$1,000 non-hidef camcorders with manual audio control). These 4 cameras do standard definition, too. That they all have manual audio controls is their key. Through a menu setting, the mic gain can be relatively precisely controlled. (More expensive cameras like the Canon XHA1, XL2 and Panasonic DVX and HVX have knobs/wheels on the camera body for the mic-gain adjustments).
Here is the link to the manual for the DCR-HC62:
I cannot find any reference to the mic-gain ("Normal/Low") menu selection.
The RODE video mics (there is a mono version and a stereo version) have gotten rave reviews - I have not used one.
I currently use an Audio Technica AT-825 for live performance recording. For interviews or where mono is adequate (or a further shotgun "reach" is required), I use an NRG SA-568. If what you are doing is music, stereo separation is a big plus. I have also found that if the camera stays in one position, having a camera mounted mic is fine - but if I want to move the camera around, I want to keep the mic in one place (especially when recording in stereo) because as the mic moves across the stage when connected to the camera, the sound (stereo spatial separation) will move with it... I put the stereo mic on a mic stand and have a long (XLR) cable back to my camera. The camera moves wherever I want, the mic stays put, no audio "movement". The other option is to use a field recorder (like those from Marantz, M-Audio, Zoom, among others) that stays in one spot and replace the camcorder's audio... And they have manual audio control.