The development overhead of maintaining separate code for each OS is too great which is why there are essentially no task management tools that cross platforms. I'd like to think that the ability to run on any platform brings considerable value to our users. For those of us that use both Mac and PC everyday, this is something we could never do with Things or OmniFocus.
Give it a second look. It may be worth rethinking the value of AIR.
I will say that getting the edge cases for sync is difficult (We also integrate with email which has made it even more complex). Having spent the last several months fighting through it I can empathize with Cultured Code's perspective. But the user community has been vocal about this issue for years. OTA sync is a critical piece of a task management workflow, you've got to have it.
I'm building some software that integrates with email (Exchange/IMAP). I'm trying to get an idea of how some of the workflow concepts would scale to people that get large numbers of emails in a day and frankly, what constitutes a "large number" these days.Right now I average around 150 a day. I think that is average for most people I know, but low in comparison to some email-centric corporate...