Thanks all for the comments. A new trick I have invented is to produce a 'colour' image for each exposure level stack before the HDR process.
So for each exposure 2,4 and 8 min in this case, I used ImagesPlus to combine the HA to the red channel and the O3 blue and green to their respective colours.
All HA and O3 stacks were identically digitally developed in IP and levels adjusted in PS before this combination.
The good bit is when adjusting the parameters in EasyHDR you are essentially looking at the final image with all the components drawing information from each of the three exposures stacks. This is far better than trying to tweak a final tone mapped image. What is happening is that you are adjusting levels and contrast and curves while drawing on the data present in all three exposure stacks. Once the tone mapping is done a lot of this data is lost and can not be retrieved.
I hope this makes sense?!
Below are the three 'colour' images that were used as input into EasyHDR. The fourth image is the output of EasyHDR. It is obvious the levels and saturation are a bit high but this is easily tweaked in PS without any image degradation.
Thanks Jase. Below are three images. First is straight color, second is narrow band and the third is colour plus narrow band by adding the RGB channels in IP. This method allows me to go very deep at my light polluted site without all the hassles of gradients etc.
You've got some great shots there. Top work. 
