Question for the experts, and from my few weeks of lurking on this thread I expect it to be a slightly divisive one: to marble floor the bathroom shower or no?

We are having all our bathrooms redone. In the master, we are having xl slabs installed in the shower and our designer picked out a herringbone honed marble mosaic for the floor. We are doing a linear drain against wall away from exit of shower (my choice, well aware of the issues if not installed/sloped properly so will watch installation like a hawk!)

Question is around the marble shower floor. Any tips on what I should request / talk with the contractor about before installation? I’ve seen the article floating on this sub (https://tilepro-usa.com/tile-pro-blog/f/marble-moisture-discoloration-dont-blame-the-stone), but I’m more looking for real world experience from installers/owners. This morning the guy said he normally uses kerdi, I assume that will be an issue here?

They are starting the other two bathrooms first, so I still have time to return and switch to porcelain floor if I can find one that matches (this was the problem originally and why the marble was picked), but I may be getting myself worked up because of some of the comments I’ve seen here so figured I’d ask.

Unrelated, but when we pulled up the tub from the other bathroom, looks like water was getting behind the old tile (second, third and fourth pics). The prior home owner I think (hope!) did themselves because it was god awfully done, wish I thought to take a picture before they pulled out. Anyway, given the spot anything that can be done with that wood? (Sorry I know this isn’t the technical forum for that but you guys all seem knowledge in general about bathroom remodels!).

Thanks 



Marble shower floor