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Once you put your mixed media work into digital format it becomes a digital work only. It should be treated as a digital photograph. The end result is a digital photo no matter how you got there and should be treated as a digital photo. Your work is good, so why transform it to a digital photograph ?
I have found that digital media works best as its own medium. I have scanned pieces in and edited/added to them, but the digital work I am most proud of is done in the program from start to finish. Digital drawings tend to have their own feel to them as a separate medium, which can have benefits.
On an other note, I would treat digital medium like a paint medium. Programs like Photoshop have many affects that can be helpful, but a lot of my digital work is either mostly or exclusively brush tool to keep the composition unified, while even using tools like burn and dodge can cause awkward inconsistencies.
I would conclude by saying if you don't already have one, use a drawing tablet.