sync should happen automatically in the background. this process should start just after the app itself loads, so that it doesn’t make the app slower to start. and sync should also be done automatically when a task is created/modified/... Evernote for iphone does this.
Comments:
this is in fact planned. The developer has plan to add background sych. Unfortunately, as of now you only have auto-synch at start and closing. And all I can do is ask for your patience on this matter.
I agree. Would be a very useful addition.