We have implemented Retail Management Hero in our 3 art galleries here in San Francisco with mostly good results. Since RMH uses the RMS database, initial setup is a breeze compared to a lot of other competitors. The biggest issue we've run into is that RMH will not display RMS journal receipts. Microsoft apparently uses an encryption on journal receipts that Retail Realm cannot use. This also goes the other way; since RMS cannot render RMH journal receipts, you cannot view them from the HQ (as you will still have to use the RMS HQ at the time of writing. RMH Central has not been released.)
RMH handles transfers a little differently than RMS in that when you receive a partial transfer, there is no option to close that transfer and automatically created a new transfer with the remaining items. This caused some confusion during our transition and was the source of multiple inventory errors.
In our other company, we've just started implementing Lightspeed Retail as that is more suiting to the needs of those stores. We are losing direct access to our sales history, but we expect to retain customers, products, and vendors.
It mostly comes down to if you want to keep an on-premise installation, or if you want to move to a SaaS model.