I'm not reading through this entire thread, but have to say that Mike's suggestion of the EX1 is one I fully agree with even if my budget can't afford it. I've dived with a videographer using one and the difference between my footage (with an HC-7) and his was like night and day. Absolutely awesome results from that system (which Mike put together for the diver). Of course as Mike mentioned international travel with that rig and housing is not easy.
I'm wondering about the HDR-XR500V. As far as I can tell, the only difference between it and the HDR-XR520V is the size of the hard drive (120 vs 240 GB?). Since I rarely burn a 60 minute tape (about 13 GB of video) on a day of diving, a 240 GB hard drive seems excessive unless you're doing an extended trip and don't edit on a regular basis.
I'm wondering about the HDR-XR500V. As far as I can tell, the only difference between it and the HDR-XR520V is the size of the hard drive (120 vs 240 GB?). Since I rarely burn a 60 minute tape (about 13 GB of video) on a day of diving, a 240 GB hard drive seems excessive unless you're doing an extended trip and don't edit on a regular basis.