No personal experience, but then again I don't think I need personal experience when judging by professional tour companies that only pick the optimal times.

When you look at the high end tour companies, they only plan trips at the best time. Look at Travcoa. They run tours to China next year in April, May, Sept and October. Why? Probably because Beijing is so hot you either hot as balls or cold as crap if you go in other months. I've been to Beijing, but only in October.

While you can go to Beijing other times of year, why would you want to do that? Do you plan a luxury ski trip at either the beginning or end of the season? You'd have to be a moron if you had the flexibility.