I just purchased the SR12 a few weeks ago, no housing yet, but I must say not having to deal with tapes is great. Also, while I know there has been some concern about image quality around here, I must say in my opinion the image quality is amazing. I don't have an HDTV yet (coming next month!), but I burned a DVD and took my test shots to Best Buy and played it on a 52" Sony HDTV/Blue-ray setup and holy toledo was I impressed. Rich color depth, great contrasts, and as you'd expect really sharp high quality imaging.
In truth my experience level with video is low, as my great passion is shooting stills, so I may have a less critical eye when it comes to this. I have previously only shot with Hi8, so by comparison it's a huge leap forward. Anyway, Ikelite and Light and Motion both now have housings for the SR12, as well as others (Top Dawg I think has one too?) so I think you should have no worries finding a housing.
While I know its highly rated, I can't speak for the HC-9. With either choice, you'll need to get some software for editing. Sony Vegas easily reads the video directly from the camera so you can use this with the Sony DVD Architect software to burn to DVD. Honestly, I probably won't do much video editing right now as my PC is a little behind the times so I only have the horsepower to burn DVDs without doing too much manipulation, but bear these things in mind as well.
Hope this helps you!