So, I have a little quandary for people who play Tech-Priests, and those who GM a group that has one or more. Your average Tech-Priest is a Human who longs to become more than that, and grow closer to the Omnissiah (possibly a C'Tan, but not the point here). In an effort to emulate their god, many member of the AdMech swap out body parts for prosthetic replacements, escaping the weakness of soft flesh for the security of cold steel. So, here's the question; How do you prevent your Tech-Priest from constantly requesting more cybernetics? Even if you aren't belabored by the The Flesh is Weak talent (HotE, p.104), an ability I am personally VERY happy they included, but can see how it can get dicey, there is no reason for the TP to NOT request bits, nor for his or her fellows to not, at least initially, want to assist their fellow AdMech in ascending. Other than surgery and recovery time, I don't see a great hold there, to stop the Tech-Priest from just becoming a robot.
On a pointless side note, is there a maximum amount of cybernetics a Human body can support? I don't remember reading one in FFG products beyond mechadendrites, and Tech Priests and Iron Hands Space Marines do long to replace as much as possible, but I don't know if they can get to 1/5 of your brain, cradled inside a metallic shell, or if, at some point, the body says "no more", like in sci-fi games of my past (Alternity and Shadowrun come to mind). I've read stuff about ancient Tech-Priests who seem completely made of metal, but I don't know if it's really doable, even ignoring the irritation to the game it might become.