Well, there are some issues with it. I never got "banned" but my account got locked when my ISP gave me a new IP. And I have a friend who like you played while staying in hotels -- his account was locked several times before he managed to get some sort of flag set on his account allowing different IPs. So, probably more frequent than .001% but unlikely to cause a "ban" without additional factors.
“Extinction is the rule. Survival is the exception.” -- Carl Sagan