Personally, I would prefer a written checklist. If Adventure Pilot chooses to make it part of IFly GPS, it could be a button labled "Checklist." From there you would click on the checklist for the appropriate phase of flight. Each checklist item would be numbered and the first item would be highlighted. You would tap each item as you compete it to move down the list. When you have finished with that phase of flight, the next phase is displayed. You would then return to the map until you need to return to the checklist. If enough people want an audible checklist, a voice application would simply read down the list.
Just now thinking about this for the first time, I think I will create a Word Document using my SkyCatcher checklist and store that on my IPad in the iBooks app. Switching back and forth between IFly and iBooks is one button and one tap away. iBooks saves your place in the last document you were using and can accomplish the objective except for the voice part.