Here is something to consider about device cost. Iphones can be expensive but with subsidies from wireless vendors they can become much cheaper than any CE device.
As far as not using the DI, that is how we have been doing it with the CE devices. The issue is that when we use this app for pick list, the inventory never gets touched until we make it to delivery. The issue here is that we cannot get real counts at any given time. This is why we are trying to make things work in real time. So far the IPhone web app is working great using B1WS.