I'm currently working in a BizTalk project where we are using WCF adapters with SAP bindings to communicate with SAP. We "randomly" finds that our receive locations loose the connection to SAP. In BizTalk everything looks fine, the receive location is up and running, but when we look in SAP the connection is down. A restart of the host gets the connection up and running again, but that's certainly not a preferred solution.
After some investigation we found that an error occurs in one of the inbound maps on the port, an error is thrown as expected but for some reason the wcf-adapter react to the error by just shutting down the connection to SAP. Hmmmm....
I googled around and finally I found this hotfix from Microsoft -
KB 950854. I downloaded and installed it and now after a few days of testing it seems to be working as expected, the receive location stops and restarts when errors occur.