With all the recent talk about DNS amp DDOS attacks, I wonder why none (?) of you LEB providers just blocks inbound port 53 traffic to all VPS?
The number of VPS users who need an open DNS resolver most likely is very small and the number of users who know how to protect an open DNS resolver is a fraction of it. It's just asking for trouble, not worth the hassle. Even though it might not affect your network in a big way, the spoofed target address of the DNS response certainly is affected.
I know there are cool tools like Iodine which will be affected by such a ban.