When I swapped from TexArrays to UDIM, none of my materials changed except for some slight logic in where I generate my UVs. Instead of appending a layer ID, I can pick out the cell in the UDIM and add to the X and/or Y appropriately.
Otherwise the rest of the material logics will be the same, there is no special accounting with where the texture comes from, it’s still just a texture.
As for the render, yes, each texture can have it’s own dimensions, so you can mix different things there if it avails you (with UDIMs).