This is AWESOME!! By the way, thanks for coming out to the CTNX this year. Loved the panels, learned so much from you guys. You have no idea how much you've inspired me (hell, you guys are the reason I invested in a Cintiq).
There is one thing I wonder about. Which canvas size do you normally work with? I mean, I've been trying to get a hang of Sketchbook Pro and inking in it, but it's still deluding me how you get such smooth lineart. I tinkered with the settings too, but frankly, I'm at a loss.
We tend to word at around 2400x3000 or above (basically 8x10 at 300dpi) We work on Cintiq tablets which helps a lot with line quality. Ultimately it comes down to drawing strokes with your entire arm rather than just flicking the wrist. We approach lines in the same ways we use traditional. Hope that helps! It can take practice but stick with it.