Not sure how you feel about parterning with other developers or incorporating someone else's features in to yours but Checkmate has a pretty good app for checklists that might be an easier and cheaper way to get the feature incorporated. I can get to it by switching apps on my android tablet with a couple of button pushes but a closer integration with iFly and the flight plan that takes into account weather, time of day info, etc.. might allow some opportunities for a "smart" checklist. (night flight vs day, IFR vs VFR, even a filing reminder if it sees a flight plan but it hasn't been sent - or closed at the end of the flight).
We've got a NRST button, maybe an Emergency or Checklist button that loads the emergency procedures checklist would be useful. Set it up like an Instrument button that could be added or not. Or pops up similar to the terrain profile display.
Incorporating some sort of checklist function to iFly is not much different than having to flip pages on the kneeboard to find a particular checklist. And if you don't have time to tap the screen you don't have time to find paper.
Tony