I think I was looking at both of these clusters last night in the Mewlon
I saw more star colour but I certainly didn't see any of the Ha
That lens is a pretty good performer Simon. Version B is a definite improvement over A.
Something else that might be worth giving a shot is using only using LinearFit on the R and Ha subs to create a Master Red channel. Then use LRGBCombination to create the RGB image.
I mention this as I've had a couple of instances when I've just been working with pure RGB images that they've ended up very red biased. I did a quick test before and found that in some instances it can be better to just create a Master Red channel and leave the G and B channels alone.
Might be worth giving a shot