Microsoft and SAP

I have a prior experience to develop .NET 2.0 based applications with SAP .NET Connector. The thing is, I was calling a BAPI function in place of RFC, I'm not sure enough if that makes difference for you but SAP .NET connector worked like a charm for me. I was accessing some internal data from a production server and implemented role based security using ASP.NET to authorize the users.

In short, SAP .NET connector is not a too bad choice.

Great News: SAP has announced release 3.0 of the SAP .NET Connector. It will support current Windows releases (Windows XP 32 Bit, Windows 2003 32/64 Bit (x64), Windows Vista 32/64 Bit (x64), Windows 2008 64 Bit (x64) and later Windows 7) as well as up-to-date Microsoft .NET Runtime versions (2.0, 3.0 and 3.5). See http://wiki.sdn.sap.com/wiki/display/ABAPConn/ABAP+Connectivity+Home and http://service.sap.com/connectors

I was working on a project couple of years ago that also used the SAP Connector. However, for system interoperability i would go for WCF these days.

I know this can be hard sometimes, but thats the best way tbh.