First of all great explanation of situational uses of chalice. As far as chalice in 5c staxs it would appear that it is unnecessary. Null rod would still allow one to play moxes to sac to smokestack while hindering the opponent. Chalice in oath plays a significantly different roll. It provides a way  of stopping an early tinker and slows combo up long enough to gain control of the game. oobviouslychalice for zero, one (if aabsolutelynnecessary, and three can be the only plays for oath.

The major problem that I have found in testing this deck is that it has huge problems playing against the 5color stacks mirror. More precisely is sucks on the draw. In most cases the opposing stax play will seek to play sphere of resistance, trinisphere, or chalice of the void on turn one thereby stopping moxen to accelerate your board position to play suppression field early. With all the tutors in the main one solution would be hurklys recall. I have found it to be quite amazing a several occasions when I'm behind on board position. Playing it at the end of my opponent's turn then laying suppression field shuts down welders on the board while letting me lay more lock componets. I have found it to be amazing against gifts and slaver as well to put moxen into their hands and force them to replay them with a sphere or two on the board. Hurkyls can single handedly swing the tempo of the game to a position where it is impossible for your opponent to win.

Chalice is not that impressive in a stax deck running sphere of resistance because chalice for two hoses part of your strategy. Yes, "if" you have a welder you can play around it but who is to say that the welder will resolve or remain on the board. In U/R and five color stax chalice should be in the board as a three of. Conversely, in uba stax, chalice is used as a replacement for the mana denial sphere of resistance provides.