The tolerances are pretty critical on the center parts, how well do they come out when cast? As for the weight I think you would be fine but you could easily remove a bunch of plastic before you start. Half of the design consideration on these parts are print ability. I would say try it with the XYZ part and see how it comes out.
With these new parts I’m not sure where the flex is coming from, I’ll have to take a closer look, plastic might be good and it could all be in the emt now. As soon as I make this SS one we will see.