I've never heard of any problems with any of those tools. But for at least the last 13 years I've never heard of anyone using any of those. Back before Keyclone was a thing (2007?) people used to try all kinds of weird setups. But way back then people were largely running 1 client on 1 PC, so stuff like software KVM's weren't really a thing for WoW multiboxing. By the time we had decent dual and quad core systems that could actually run multiple clients at the same time, software tools had come along so that we all stopped trying to build our own.

As you look at different tools, try to find software that can only do 1 keystroke is 1 in-game command to 1 client. If you find any software KVM's that include options to do broadcasting, then stay away from those.