After looking for a mail client that will sync tasks as well as mail and calendar I have found two, Nitro Touchdown, and Moxier Mail. Both are not cheap at £13 give or take a bit and both seem to work very well in the 12 hours I've been running the trial versions. The stock mail client on my galaxy s2 has stopped syncing with my work exchange server after the ICS update (and what a waste of time that was, phone is now even less stable than it was); and in any case it would not sync outlook tasks. One feature of Moxier is you can make an email a task which is very useful for me
Anyone else used either? the one big difference I have found so far is that Moxier cannot integrate the contacts database into the phone dialler, whereas Touchdown has. Not really an issue for me as I don't use the contacts list from Outlook.