Like others have already said, my only concern would be whether a store would accept a printout of the original receipt when returning an item. I personally believe that the data on the paper is the important part, and not the paper itself, but I just wonder whether a store would agree.
I forgot to print my pre-purchased movie tickets before going to the theatre one day, apologetically showed the PDF tickets to customer service on my iPhone, and I was good to go. Not the most efficient way to get into a theatre, but the data on the receipt was analyzed, not whether it was with ink or pixels. Now try that with something more than a $15 movie ticket and see if it works.
