Change or Die
Small retailers need to select a POS Software company that can act as their technology staff as well as furnish them software. Never let price be the first question asked, but how is your support and service followed by functionality of the product and will it fit my budget. Small retailers also want a product as good as the big box retailers use, but at a price that can fit their budget.
To try and have the new software work just exactly like the old is a recipe for disaster. This is where the term change or die comes into play. By the time you program for the old functionality, de-bug and go way over budget, the gains in productivity are mostly negated. The POS software you select to improve your business should be 95% of what you are looking for, straight out of the box and return on investment must be your top priority.