Nice image David
Do you mean HDR wavelets or the HDR Composition tool?
I'm in the middle of processing M42 with PI and found that lowering the binarizing threshold in the HRD comp tool helped me produce a nice smooth transition through the core to outer parts. My core also has come up a bit mono in colour but adjusting the curves slightly (in PI not PS) brought some colour back - I used a range selection mask to just work on the core.
I am using OSC camera though - may have a different effect on results as well.