Photomatix 6 beta is available for testing.
I downloaded Beta 5 this morning and here is a quick comparison with Photomatix 5.1 This info appears when you fire up the Beta test:
Photomatix 6 using the new Tone Balance Method
Photomatix 5.1 using the Contrast Optimizer Method
In both cases I used 20% Austo-deghost to "fix" movement of foreground vegetation. Assessment will continue but my first impression is that the beta handles shadow detail much better than Photomatix 5.1