Ask HN: Review my Startup idea - Sync Things Done.

(Sorry about the mispost.) I've been looking at both desktop and web-based software for David Allen's "Getting Things Done", but one thing I haven't been able to find is a service that lets you sync your project and action lists between the web, computer, and smartphones, si I've decided to fill that gap. Does anyone think I'll be able to succeed in this alresady saturated market? Or am I wasting my tmie?

As always, thoughts, comments, and suggestions are always appreciated. Thank you.