I'm no expert at it, but your surface image portion seems to be quite banded or solid on each side. The centre portion seems fine.
I use autostakkert instead of registax. From what I understand, autostakkert is more up to date. If I use registax, it's usually after processing in autostakkert and it's for the wavelet processing.
I use the same camera, but with a Coronado. Here's a couple of my attempts from earlier this year:
https://plus.google.com/u/0/+ChrisRy...ts/LhgexyoM7QJ https://plus.google.com/+ChrisRyan_Oz/posts/1gbX2WANPve https://plus.google.com/+ChrisRyan_Oz/posts/8ZJDAc5XqnX
For processing the proms/flares, you may need to mask the main sun disk so you can enhance the detail. I did that for the last link above. If you want to include the main disk and the enhanced proms, you just have to put them back together after processing.
I suggest going into the Solar imaging section and posting a reply to some of the people there posting Solar images - they can probably give you better info/tips.