It's a bit funny, whitout seeing your post, I just try to reduce the two gradient and yes it work. But it's doesn't give the original impact I was firstly try to achieve.
I also try again the motion blur, whit an angle of 42 for the upper banding who also work well. But there still some artifacts who afraid me a little. I just try to have a correct background
Now I think my problem is mostly a technical one. First I must try to buy photoshop CS2 or 3 for at least having the adobe RGB color space available. Another thousand queen heads away
Then if it's don't work again, shoot in RAW at 12 or even 14 bits.
But do CS2 have this 12 and 14 bits option. The 6.0 have just the 8 and 16 bits?