ASC controllers are very simple thus reliable, though basic and of a single stage PWM type. To start (what I have done), you could enhance your present ASC system by adding a in-line shunt in the ASC's output which will allow taps for a separate digital amp meter.
Future expansion could be made with a parallel solar system (with dedicated controller), inverter, and if you like, add another 500amp shunt in the Batts neg cable for a stand alone smart meter like a Trimetric or Xantrex LinkLite...In this way, you'll see what either system is harvesting real-time (separately or combined), and total amps both in & out of the Batts...
Here's a link for a Shunt:
http://www.bestconverter.com/search.asp?keyword=shunt&search.x=11&search.y=10
3 tons