The ONLY problem with Keyclone is that you need to buy a license for every system and that license has a unique key to that system. So, if you change your hardware setup or have to reformat or otherwise change your system, there is a chance that Keyclone will break. However, if this happens, Rob has been very responsive with the fix.
HotKeyNet is free, works great across your LAN on two or three systems, but is a little tougher to setup. If you want to run more than two WoW clients on one system, I suggest InnerSpace + Clickboxer. InnerSpace does a superior job with window management. Swapping from any sized any resolution window from background to foreground or PiP is much, much, much faster than anything else that I have tried.

-j