catachan models are better
trust me ( as wierd as it sounds)
If I had the option of uploading my favorite conversion I would show you, it just that they are so easy to work with and cadian models are icky to me.
catachans on the other hand are not as nice to see with lasguns. So I opt for their laspistols and catachan knifes. (for the WYSIWYG I coverted a number of my catachans with lasguns, and got some cadians for the hell of it. ) It is easy though to attach firewarrior arms to a catachans torso ( perks being that tau arms connected to pulse carbines and rifles) mix that with some vomit brown, or a skin oriented color and your finished. If you dont like the rough image, smooth it down to the point that it looks like a normal unarmored hand.
IF you want tips pm me and ill gladly give you my experience with them. plus what to say if people complain about you using them.