I use KD with Executioner as a standard tanky weapon, for pure threat. I will farm mech at some point to do what you have and get Sun Eater as a avoidance weapon in my bag (as SSC could be a while off). It certainly won't be money wasted and if you already have a mongoose weapon then the alternative option could be quite sensible.
Plenty of people do use mongoose on KD and seem happy with it, so it is somewhat personal preference, but I can't see you being unhappy with the result, if that helps.
Former TBC/LK Tank
Waiting for Dunmail Jnr to sleep to enable online gaming.