The only TP I have seen with robot bits is that one in the trailer reading the book. When i roll mine I want not only that spiffy axe of the omnissiah, but some cool robo appendages to wield it.

but how would the devs add Mechadendrites without them being just fluff...i mean i want them no matter what, but I also want to relieve my days of tanking as a TP in DH cause i had a hydraulic wench attached to me.

appendages seems likely to me, but i think if they use it as an armor slot for the tech priest, it will be appendages as a whole. Although i must admit it would be sick to be able to customize each appendage.