The AVCHD format is being used on quite a few cameras now. But I believe only Panasonic and Sony are pushing the boundaries with AVCHD and have cameras which can record at 1080 50p in AVCHD.
I think what I wrote came out wrong, what I meant to say was editing non progressive files are easier as the demands on a PC and editing software are lighter. But the results when playing back interlaced video on a progressive platform (anything other than your HD TV which knows how to handle interlaced video) such as youtube and your PC monitor etc can vary depending on how your computer is dealing with the interlaced nature of the video.
It's quite brain aching! This is quite a useful link which explains interlaced video quite well a long with the problems and limitations of it and explains the benefits of progressive video.
http://www.digitalphotographywriter.com/2010/08/hd-1080p-vs-1080i-videos-progressive.html
You will need a very decent PC to edit progressive video since the editing software will need to process twice the amount of frames compared to an interlaced video.
The SD600 has had a little criticism by some for the noise generated by it's cooling fan to cool the 3 sensors. This fan can be heard on recordings in quiet rooms and since there is no mic input jack it is impossible to use another an external microphone to isolate the noise.
It might be something that would bother you.
I believe that the SD600 is soon to be replaced by the SD800.