[gazhayes]

There are already a number of web based apps that support GTD much more completely than OF does, they just don't look as nice.

OF's major selling point for me is that it works VERY well on desktop, tablet, and phone, keeping in perfect sync without needing a solid data connection all the time, and it does this on all these devices in a sleek and user friendly manner.

Nothing else meets on the market really meets this need as well as OF.

If they were to release a Windows version, it would have to be a LOT better than all the other Windows and Web only competitors for anyone to use it (considering they are generally a lot cheaper than OF, or even free), and that is going to be an uphill battle. They would also probably need to release an Android and Windows Mobile app to go with it to remain competitive. Otherwise the only Windows users they get will be people who already have the Mac version but want (for example) something to sync with it at their Windows only workplace. It would be tough to make something financially viable.

Personally I would love a Windows version too, but also personally I would not want to risk funding it's development.