I have two, both close to monti's.
Don't seem to bother each other although I had one monti "reach out and touch" the scroll and attach to it. Still kalking it to kill it!
I've found the Ruffled Ridge (scroll) to be hardy but not a fast grower in my tank.
It does appear that the healthier they are, the darker they get.
The one in the picture seems a little stressed as mine was like that when I first got it.
Now, the colony is a dark mustard with brighter yellow polyps and bright yellow edging on the colony.