I've just found out that MS Todo can sync with Outlook tasks. I don't know why I didn't before but it's exactly what I need.
I was thrilled to find that Todo also has 'steps' as this will cut down the overall number of tasks I need.
What I'm not so happy with is that if I make a change to the task on Outlook, it wipes out the steps completely. I can understand Outlook not understanding steps and therefore just ignoring them, but is this behaviour by design or am I doing something wrong?