If you have run Helladrol before solo then I would say to add it in and you might see better results. It really depends on the user but you feel that the helladrol run is not enough for you, then stacking it with the nonmethylated katana is a great idea
I've seen many use this stack to lose weight on the forums. Is it too much? Who really knows, but if you have the stuff and want the BEST results bodycomp wise I cant see why this wouldn't be a good idea.
Running katana solo... hmm... Id say you would need around 300-400mg ED for it to be useful. I really don't think a 4x cycler would even feel much of Katana... .but then again I have never run it solo, nor have I seen many logs of it. Would be good to test though if you wanted to.