Upvote:3
I hear both Popayan and Pasto are quite safe to travel now. You shouldn't have any problems. You can take extra precautions by taking bus companies that travel directly to terminals, and by traveling only during the daytime.
You could also read these forum posts, they are quite helpful.
I did the Pasto to Popayan route 2 weeks ago, then went on to Tierradentro from Popayan. Everything was quite safe, and there were many many foreign tourists enjoying the beautiful streets in Popayan. (Source)