I've received 2 emails asking me about which 3xsensor camera to get (how DID you guys get my email anyways? It's not listed!) and particularly the Sony V1 and its problems shooting 25P.
I've always been a big fan of research and alternatives. Sony is so far entrenched as the defacto brand for u/w video. Well it was the evil empire of sorts in the 80s and early 90s when hi8 was the DV of the day. Still, Sony cameras are not perfect. They have a tendency to overexpose, the colors and contrast look harsh (the Sony look) and controls lack finesse.
Right now, Sony has the HDR- FX1/7 and HVR-Z1/V1 as their top consumer and prosumer 3 sensor cameras respectively. The HDR-FX1 and HVR-Z1 have been on the market for almost 2 years now. They were the first 3 sensor HDV cameras on the market and quickly became entrenched in broadcast news and TV production work. The Z1 is the only camera that comes with the ability to shoot 50i(PAL) and 60i(NTSC) built in(The Canon XH and XL series have it as a factory installed only option).
Then recently the HDR-FX7 and HVR-V1 were released. Designed as a more compact camera, the 1/4 CMOS sensors boasts less smearing, better color saturation, detail and resolution. The V1 of course boasts the first 1080 HDV camera to shoot in progressive scan natively (the Panasonic HVX200 shoots in DVC Pro HD). The V1 boasts knee and black controls as well, making it a viable alternative to the HVR-Z1 for many applications. With this combination of 4 cameras, Sony has a very strong offering and continues to dominate all housing manufacturer's catalog.
However, I believe in competition and there are better alternatives to the Sony cameras. Canon's latest 1/3 3CCD camera, the XHA/G1 is one such camera. It shoots 1080i HDV but the sensor is a full 1440x1080 vs 960x1080 of Sony. The resulting picture has better resolution and detail as well as very nice colors and "look". It has a lot more image controls giving the user superb control over the look vs the Sony approach of "we know what you want so let us do our thing!" fewer image controls. The autofocus on this camera is superb, definitely the fastest and most accurate of all HDV cameras right now, esp in Instant AF mode. Not that the competition is bad, but the Canon is just better. From what I've seen, the XH is probably on par with the Z1 for lowlight shooting and produces better details in the shadows. The 20x lens is sharp and there's even a separate ring for iris/exposure control, not some little switch. It can also shoot 50/60i (PAL/NTSC) once the optional upgrade is done and still falls in just under the HVR-Z1 price. It is definitely a strong alternative to the Sony offerings.
Unfortunately, only Gates is even thinking about a housing for the XH at the moment (although they have one for the XLH1). Even though it has lanc, the electronic housing manufacturers are not supporting it. Hopefully, that will change as time goes on a proper review of the camera used uw is done 
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I also have to mention the Panasonic HVX200. It is STILL the best slow motion capture camera at 720/60P, bar none. Sure the sensors are smaller and the resolution not as high as the other cameras. The biggest problem it has has nothing to do with image but storage! The P2 DVC Pro HD system is awesome but prohibitively expensive and also lacks recording time. The largest P2 card available is 8GB (16GB is out very soon). 2x 8GB P2 cards give you 16 minutes of 720p, not exactly very long and also $1400 for each 8GB card. You could use a hard drive recorder like the focus enhancement FS100 but then you need a separate housing and a live firewire connection. Not a very practical solution.
Still 3 manufacturers sell housings for it, Seatool, Gates and Aquavideo. And for all the complaints about the storage, the 720P clips looks great! And the P2 (.mxf) file system is the nirvana of editing, so simple it is to copy to storage and edit.
So which one is my favorite? I think I've not been shy in showing my liking of the Canon picture quality. Plus they actually give their cameras 1 year full warranty vs 90 days labor of Sony 
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Most importantly, having competition against Sony can only be good for consumers like us. The V1's progressive scan was a direct result of Panasonic's popularity with DVX100 and HVX200. We have better choice for our money and it broadens the market.
PS. I know quite a few would like the same roundup of single sensor cameras. It's a matter of time constraint. There are 7 3xsensor fixed lens cameras out there. With single chips, there are ones with AVCHD and HDV, so it's a lot more to cover. Plus I'm biased to having 3 sensors instead of one. 
