I'm not so sure you need an underwater camera. Are you actually wanting to take it underwater, or are you just afraid that some splashing will ruin a regular camera? I don't own a rugged camera, but I've used my decade old digital camera in wet conditions including rain. Mind you, I try to keep it dry, and when it does get wet, I wipe it down immediately; I don't wait for water to seep in.
IMO your main concern should be the camera's performance (especially in low light), and then how rugged it is. A rugged camera would be of no use if it takes lousy low light images. But if you still want one, of the two I would go with the AW100. I've read the Sony's touchscreen doesn't work underwater, and I've also read reports of the sliding cover getting fouled from sand and debris.
Looking to buy a underwater camera that will cover me through my travels through south east asia as well as back home here.. will be riding in rivers going full moon parties etc so obviously the water factor is a needed one here..
Only thing is I have nutted it down to these two cameras except there are not many good comparisons between the two cameras!
Many say picture quality is loads better on tx10 others dont agree.. aw100 looks like it could withstand more than the tx10 and the tx10 slide cover thing looks like it could do more damage than protection to the camera...
Which would you choose.. dont think the ft3 or whatever it is sounds the best as many have problems with them and there out of water shots arnt that flash.