On the journey planner front, the Trainline-powered planners happily recognise Liverpool Street as an appropriate London Terminals station whereas the WebTIS planners only recognise it as part of a zonal group. I have no idea what the other journey planners do, except for the National Rail planner which lies in the first camp.
Although the walking distance between the Stratfords seems reasonable, has it been made clear whether or not the DLR will accept point-to-point tickets between Kent/Essex and Liverpool Street/St Pancras respectively?