"Ouch" if you are relying on features not supported in older versions but a manageable problem from a QA perspective.
That number is not too far off what browser update rates were 5-10 years ago. On the browser side, updates have got much more seamless (and app updates are pretty painless) but an OS update is still a big deal.
Loving Boomerang. I send an email & set it to remind me if if there's no reply within x days/hrs. I use it for intro requests, bizdev, even emails to my wife that I suspect might slip through the cracks. :-) http://bit.ly/1j0tgmi