For the price of 12 drives you might be better off buying a massive RAID, which will work as a back-up itself.
What I would also consider is a small camera recording in H.264 (like Aptec), something you can edit in FCP.

Thanks Robert, I don't really have mains power, only 12 volt in my Land Rover, so I need to use bus powered USB and FW800 drives (only one, stupid new mbp's only have one port ;-) and power the mbp through 12 volt (which in itself is a challenge because of the patented magsafe connecter!)

Do you have a weblink to the Aptec you mention, thanks?

John, this is the link: Aiptek | Action-HD 1080P High Definition Camcorder | A-HDPRO

Thanks mate, the Aiptek's look good for knock about cameras but again don't do 1280 720 at 50fps - so back to the same problem as with all of the others.......

It does 720/60p, so I bet PAL version would do 720/50p

What would happen if you dropped 1080i50 HDV and 720p50 footage from the HM100, onto a 720p50 timeline, with FCP? I've never tried it, but I bet it would work fairly well with Edius. (I haven't touched a Mac in decades, and have no idea what you can do with FCP.)

Again, there is no PAL version - idiots!

But I have run out of time, so I have ordered two of the Aiptek AHD Z500 plus cameras, plus a waterproof case (mainly for amusement!) as it does 1280 x 720 (same as the HM100) at 60fps.

60fps should convert to 50fps with the minimum amount of pain that I can get away with all things considered.....

Many thanks for the tip Robert, I had never heard of Aiptek before, and the price is half that of the Sanyo I was looking at, so although I'm sure the quality will be lacking in many areas, I will be able to strap one to the chassis whilst driving across rivers and not have to worry about losing an expensive camera. It doesn't matter too much about the quality of the shots, as long as the crocodiles show up.

Huge amounts of thanks to Bob as well, who without his test footage would never have gotten me started with playing around in FCP and mixed timelines (have been googling alot!) at a time when I have plenty of mechanical things to sort out etc etc

Thanks guys, lets hope it works out ok!

www.aiptek.eu - PocketDV AHD Z500 PLUS

You create a new timeline sequence in fcp at a set size/frame rate. You add some footage at that size/frame rate. Then when you try to ad anything else, it asks if you want to convert to the sequence settings. If you say yes, it converts(?) using prores.

Very easy really, but I have no idea how this effects things down the line......!

Might be worthwhile to get your hands on some 1080i50 footage, and experiment a little bit.

John, a reporter from a local station used Aiptek while shooting a story, looked OK, even for broadcast. I am sure they had to tweak the footage, but really while watching a story for 3 minutes I did not even think about the quality. Just remember you probably should not use over 20-30% shot with such cam.

If it were me, I'd certainly prefer to deinterlace and downsize 1080i50 to 720p50, than convert 1080i60 to 720p50. I don't know what's available on a Mac, but with a PC I know I can do the 1080i50 to 720p50 conversion pretty nicely (at least with most any typical footage) without a whole lot of hassle. Taking 1080p60 (or 720p60 to 720p50 though, would require either simple (crude) frame decimation (which can make for less than ideal judder - little jumps every 5th frame - ok for some footage I suppose, but not so great for other types of footage, like slow panning for example) or getting a heck of a lot more involved with frame interpolation (like with something akin to Magic Bullet or something like that).