I uninstalled Flash on my Mac about a week ago. Wanted to see if I could reduce the fan noise and heat. The one thing that might make me reinstall is that YouTube only supports 1 in 10 videos in html5, if that.
http://www.verticalforest.com/2010/06/09/youtube5-html5-conv...
Chrome keeps its own version of Flash, and if you quit the browser once you're done with the Flash page the Flash processes won't hang around beating up your computer.
I've been happy with Click to Flash and appreciate having the ability to turn it on when I have to have Flash (Google Analytics, Pingdom, YouTube, Slideshare.net, Vimeo, Pandora, etc). Unfortunately, I just don't think it's possible to run without Flash and still be able to achieve the productivity some of the prior mentioned Flash-enabled websites give me.