Thanks so much Stryker and all. :-D
I wouldn't have a clue how to calculate the number of pixies or whatever magic you said makes these computers 'go', so will see if I can twist a developer's arm to do it all for me, and then will keep Twine as a close second depending on the cost.
With regards to sales, I'm actually pretty sure the app will be free (including no commercials). It's definitely more of a passion project.
I've actually been enjoying the book assembly and light coding/scripting aspects of this site's bookbuilder (although, ironically, I haven't been able to get font changes to stick!), so I think I would like Twine.
With regards to happily curling up in a ball and going around singing praises of ink/twine... Would I have to be rolling or can there be some sort of a wagon? :-)