Trazyn is nice because he is scoring and he doesn't die, it also helps you beat Boyz-blobs.
Imothek is awesome because of the Night Fighting that goes on forever (Chrono-awesomeness).
And Zahndrekh gives you all those nice abilities.
In my opinion Orikan is overrated, but that might just be me.
And are you sure you want to do the C'tan-trick in this list? He's quite expensive and he doesn't directly support your Disco Inferno. You can also take armour saves against failed
DT-tests.
I would have to calculate it, but I think Imotekh does more damage for fewer points.
Also remember that the C'tan needs at least two powers!
My next Necron-game will be a RCDI-list

I just need one box of Lychguard to make myself some Crypteks.