Wow, I can't believe they haven't built a centralised solution and that they think web-based sync is slow because of all the disk accesses. I don't care how big their user-base is, they are still only storing tasks - not images or videos.<p>Client to authorative server sync seems to be the way to go to me… it doesn't have to be live (they could queue up the syncing asynchronously) and they could control whatever subscription model they decide to put in place for one of the most expensive task management apps in existence (especially when you buy a copy for your Mac, iPhone and iPad).<p>For example: Remember the Milk seems to have solved this problem without having a slow application, and they have a web-based version (the default) of their app to boot with more features than Things would have.<p>I think the problem is they approached the wrong 'web developers' when they asked for a synchronisation solution. I could easily see 5+ million users on a single, active DB server with under 64GB of RAM being able to hold a complete index set in memory and being able complete 10,000+ queries per second with communication occurring via a queueing product like RabbitMQ or ActiveMQ or a custom long-lived Java/NIO web server written in under a couple-hundred lines of code to keep connections open to 100's of thousands of devices simultaneously (<a href="http://blog.urbanairship.com/blog/2010/08/24/c500k-in-action-at-urban-airship/" rel="nofollow">http://blog.urbanairship.com/blog/2010/08/24/c500k-in-action...</a>).