Interesting that you should bring them up: I was just looking at them today and requested some more information from HMS.
I haven't thought about using them in place of a 1761-NET-ENI or Digi One IAP, in which you would access serial-only controllers via RSLinx Classic.
I think of them more as message gateways for dissimilar protocols, like allowing you to connect to Modbus or ASCII devices over EtherNet/IP.
My applications need a custom query/response protocol. I could use the Prosoft MVI69 modules (the controller is CompactLogix) or a POINT serial module, or maybe these.
So in short: No, haven't used them. I've other HMS devices like the Anybus-X and been very pleased. Rockwell Automation actually cross-licenses hardware and firmware with HMS for some variants of the Anybus-X, and I know that the HMS Communicator sometimes wears Groupe Schneider green labels too.