Heard them both when looking long and hard for an integrated. Initially heard the CAP151, which was very good overall - nice, black background, spacious-sounding (good breadth and depth), fast, transparent...
Next day listened to the CAP101 - the magic collapsed... not as clean-sounding and dimensionality was lost to a large degree. It just didn't compare.
I spoke with a rep at Classe and discovered that the preamplifier stage is MUCH different between the two. He, of course, suggested that I stretch my budget and go for the 151 because it's so much better.
In the end, I didn't opt for either one.