I voted in favor of allowing any client because a somewhat similar situation was faced by a StarCraft private server called ICCup. They had their own antihack launcher that works effectively, but the problem was that people wanted to log in and play without the antihack launcher(the server required that you load the antihack before it lets you connect). The I in ICCup stands for "International" and to increase the population, ICCup compromised by allowing clients without antihack to play but still gave an incentive to use the antihack. Generally people from spanish speaking countries dont load the antihack, but they make up a decent size of the population and so are important to the health of the server. Even I still see stubborn people on Bnet servers who refuse to accept third-party tools that don't even give a gameplay advantage, you'll have a difficult time convincing some people to use a different client AND a launcher to play; realize that literally every additional player makes a difference on a server this small.