I'm thinking of it from the how I like to work. As it is, I like to take photos in the field and edit at home. I like to organize and edit on two large screens. One for large thumbs, and the other for the current edit. (Both in a properly lit, aka dim room, both set to sRGB - because that's what I have and what most places will use anyway.) I like a mouse and keyboard at my desk. They're fast, I'm good at making selections with the pen tool, and shading masks, etc very quickly, and I know what keystrokes do what (at least in LR and PS6) I tried to get used to a wacom, but in the end the mouse is faster for me... for retouching. If I were an artist drawing freehand, I'd totally go for a pen input, but not for photo retouching. However, this is how I like to work at my desk. In the field, I might not even have a desk. If a mouse is out, I'm not sure how I would rank retouching with a trackpad vs a pen on tablet? When i write, I like a keyboard.
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