Bit late, I've already done that. :) Although I don't remember hearing any horror stories, other than an amusing anecdote about how his ultra-free netbook wouldn't connect to the wireless, whereas the proprietary Macbook worked perfectly...
Why would you expect any different? Wifi is pushing the bleeding edge of how proprietary a technology can be. Short of buying a semiconductor fab and replacing every access point and wlan chipset on earth, there is not a lot Stallman can do to prevent this problem. (Even then, the FCC does not care for radios that can be modified by their users. So this is why he has to advocate for Free Software: it's already illegal in some applications.)
http://www.ukuug.org/newsletter/17.2/#repor_paul_