I commute by bike (2x30 min/day), go running 1h30 once a week and have a rowing machine (1h/week). I don't want to live without these highs. It also helped me in productivity and mental illness.
"For pet projects I'd be inclined to give a green light. It's always nice to play with new technologies as it opens your mind and give you new ideas."
I had no success in learning another languages now that I know D... be cautious :p
"For full fledged commercial products you expect to live several years, that's going to be a solid red light. I wouldn't take the risk of using an unsupported language."
I would have said that a year ago, but it becomes less true over time.
You are likely to encounter less bugs in D1 than one year ago. DMD is released frequently, usually fixing a lots of bugs you didn't even worried about.
All problems other than compiler bugs aren't really blocking. There is also bugs in C++ compilers.