The Crimson Circle are Vlad's followers yes:
Even so, under Vladimir’s tutelage, the art of hemomancy has found a place in the military of Noxus, and among scions of the old aristocracy. Among these diverse practitioners is the Crimson Circle, a youthful cult dedicated as much to Vladimir’s personality as to blood magic itself.
And it doesnt really matter how secretive the Rose is if your leader is literally one of their founders. And I wouldnt say they're good guys just because of opposing the Rose, we have seen in Art is Life Vladimir wants to leave the Rose to do his own stuff:
...a midnight flower with roots in old and corrupt soil. We have danced, she and I—oh, how we have danced in blood over the centuries, but the tempo of the music has changed, and the dance nears its end. This parade of fools I walk among, this life… it is unsuited for what must come next.”
“I don’t understand. What is coming next?”
“At almost any other time before, I could have answered that with certainty,” continued Vladimir. “But now…? I do not know. All I know is that I must change to face it. I have been passive for too long, and allowed flunkies and hangers-on to fawn over my every whim. But now I am ready to take what is mine, that which was for so long denied me—a kingdom of my own."
So unless you count helping Vladimir to create a kingdom of his own as "being the good guys" which I really would not, I dont really see why they would be considered as such.