None of the good data about an endpoint is available via API calls. Cisco believe that all their profiling data is the key to the product and will not expose it other than the ISE EAT tool (https://iseeat.cisco.com/). I dont know about the future of the API, but the data you can get about an endpoint is minimal (very frustrating that this is true).
Query the M&T for current session data is terrible for anything other than a small deployment. I tried collecting MAC to IP mappings from the M&T API calls on a larger install and it was taking 10-20 seconds per query to get an answer for one MAC address. I swear the M&T was going through its table line by line, "Is this the right MAC?", "Nope", "Is this the right one?"
