SAP is one system where people do not like to run things under a service account. They want to see transactions being recorded with end user name specially when posting data back to SAP. Most of them are fine when it comes to reading data with service account but not when it comes to posting back data. I have also recorded a short video on a unique and highly desired capability of using SAP end user credential to execute the AgilePart at runtime.
This has been one of the biggest hindrances in using SAP connector. If you look at some of the SAP connector videos out there on Pluralsight or other training sites, they too would say that while writing any .Net code to connect to SAP you need to use service account. However that is not acceptable to SAP admin so adoption is low.
Most product out there use products out there use service account and then there are few which try to work around this by asking user to enter username and pwd in clear text and store in form data which will be a security flaw.
With AgilePoint NX, you can actually make this happen in a secure way. Please look at the video to get familiar with it.