Then don't upgrade.
For some, the additional functionality available will improve sales. For me, if spending 6 grand would increase sales in one of my locations 1%, then the investment is a no brainer and a great investment (Yes, I know that for some, maybe 1% isn't as much as other concepts). The final decision is yours and only you know your business needs, and if the product is worth it. If not, then spend the money somewhere else. But, if these other, "large" customers are using this product widespread, then it might mean there is something of value that they have found and proven during testing. Nothing wrong with stealing ideas from the big guys.
If nothing else, call them and find out what they like about the product. Most of the POS/IT staff (Directors, VP's or even Managers) at these companies are used to people calling and asking questions about products they are using. Outside of security products, they will usually be more than happy to answer your questions.
Others here keep stating how Radiant is pursuing large customers like me. You bet they are, but they are still more aligned for smaller companies that have no IT staff, or minimal IT staff. This is evident with how many of their products (And newer products) they are providing are hosted solutions, whereas with larger customers, hosted solutions are not feasible, and it is usually cheaper to either build or self-host a similar type of product.
Overall, Radiant does provides a good mix for any size concept. There are many POS solutions available that provide only to large scale customers, and other companies that can only provide to smaller concepts only. Not too many can actually go both ways, despite what any sales person says.
MegabyteCoffee.com