12. is a tough one, and is the reason that businesses often choose 11.

The danger of soliciting input is that people often couple too much of their ego with their suggestions. You can't possibly go with every suggestion or incorporate all input (because let's face it - most of it is usually poorly thought out), so when you give everyone their say and then have to go a different direction from much of it, people get angry and resentful.

I worked with one chap who literally hung onto his discarded idea about a bit (seriously, a bit field in a database) for years, with it reappearing with a bitter sense of pride with every new database discussion.