Thanks everyone for the kind comments, glad you liked it!
Ian, it's a good question (if the 60Da would do better than the 60D) - I'm not sure there's very much H-alpha in this region, so I would guess not, but I'm sure the better imagers could say otherwise!
Andy, I'll have a go warming it up - colour calibration without a clear white or black point is tricky so you could easily be right!
Though I do like the Sidonio approach to colour saturation