I actually block Baidu. A review of my logs revealed they were vacuuming down my websites...
I've blocked Baidu too. Was a major pain doing. It uses a number of varied C-Class IP's. My concern which IMHO should concern others, is the Baidu bot ignores robots.txt directions.
The damn thing crawls whatever it likes!
In addition it kept returning, most time multiple times a day and sucking down the same pages...I blocked this and a couple of other rogue bots across my network of 30+ sites. Add up all the bandwidth across all these sites being hit multiple times day in day out and it staggering how much wasted bandwidth it uses.
My advice is block Baidu, it's a useless bot and SE.
NB - block in your .htaccess file (unix) or (win box) similar. Don't bother with blocking it in your robots.txt file - it take no notice of it.