I have owned Callistos and currrently own C3s. I think DF nailed the GMA sound when he described it as natural and coherent. I have also owned several pairs of Montana speakers culminating with the model you mention. While Peter's speakers are very good, they cannot compete with Roy's. The EPS2s are musical and very easy to listen to but don't have nearly the resolution, timing and transient snap of any GMA design. I replaced my EPS2s with Callistos, if that tells you anything. I have never heard the Calypsos, but I can only imagine they are very similar to my C3s, but on a smaller scale.
Shakey
Shakey