Help needed on background transparencies again..sorry

[mightyfun]

My issue seems to arise when trying to export an image in jpeg, or png files while making the drawing true, or true+alpha color.

I don't have any problems making a transparent background with a lesser color selection. However I don't get a soft clean look to my feathering when I use the lesser selection.

Would someone be so kind to tell me how I can keep the integrity of the drawing and still have a transparent background?

Thanks in advance for your help,

Jen