>>these device are going to be give to the customer while they walk around the tables and
>>make the order
>>currently we use a clipboard with 3 pages, 1 pen, 1 number Card

>>the question still remains Can I replace the clipboards and papers with eReaders? 

Maybe you should test the process first. Knock up a little spreadsheet, put it on the reader and walk around and order some product and get it picked and packed.
Then compare it to using paper and pencil.
I suspect in a non-automated warehouse and a range of staff, the paper will win.
I also suspect paper is less environmentally damaging than electronics.
Paper also has longer battery life.
Not as much fun though ......

